@@ -8,6 +8,44 @@ [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
 
+## [1.4.0] - 2026-04-17
+
+### Added
+
+- **Multiple reading modes** via new `-r/--reading` command line option:
+  - `evangelion` (default): Gospels only (Matthew, Mark, Luke, John)
+  - `new_testament`: Entire New Testament (books 40-66)
+  - `old_testament`: Old Testament only (books 1-39)
+  - `bible`: The entire Bible (books 1-66)
+- **Flexible Bible source support**: Can now work with any Bible translation
+  - Removed hardcoded Polish book names
+  - Reads `book_name` field directly from JSON data
+
+### Changed
+
+- **Date progression system enhanced**:
+  - `NewDateProgressionWithReadingMode()` accepts reading mode parameter
+  - Calculates verse positions based on selected reading scope
+  - Proper wrapping at boundaries of each reading mode
+- **Formatter now requires Bible reference**:
+  - `NewFormatterWithConfig()` now accepts `*Bible` parameter
+  - Formatter retrieves book names dynamically from loaded Bible data
+  - Updated all formatter initialization calls in codebase
+- **Book name handling refactored**:
+  - Removed `polishBookNames` map from `verse.go`
+  - `BookIndex.String()` returns numeric fallback representation
+  - Actual book names sourced from Bible JSON metadata
+- **Configuration system enhanced**:
+  - Added `reading_mode` configuration option with validation
+  - Command line `-r/--reading` overrides config setting
+  - Improved default value handling for empty configuration fields
+
+### Fixed
+
+- **Configuration validation**: Allow empty reading mode during initial load
+- **Build errors**: Fixed Go compilation issues in configuration unmarshalling
+- **Backward compatibility**: Maintains existing behavior for default mode
+
 ## [1.3.0] - 2026-04-17
 
 ### Added
@@ -100,9 +138,8 @@
 ### Changed
 
 - **BREAKING**: Changed from bookmark-based progression to date-based progression
-  - Previous versions used `bookmark.toml` to track reading position
-  - New version calculates position from current date
-  - Backward incompatible with bookmark-based usage
+  - Previous versions used `bookmark.toml` to track reading position, new
+  version calculates position from current date
 - Restructured codebase with modular Go packages:
   - `internal/loader.go`: JSON Bible data loading and indexing
   - `internal/dateprogression.go`: Date-to-verse position calculation

@@ -46,6 +46,8 @@ Default macOS and Windows paths are also supported.
 
 ### Configuration Options
 
+- **reading_mode**: Reading mode: "evangelion" (four Gospels; *default*),
+"new_testament", "old_testament", "bible" (default: "evangelion")
 - **output_mode**: Output mode: "tui" (interactive terminal UI), "formatted"
 (ANSI-coloured text), or "plain" (plain text)
 - **bible_path**: Path to Bible data file (default: "books/pol_nbg.json")
@@ -88,6 +90,8 @@ ### Command Line Arguments
 
 Command line arguments override configuration file settings:
 
+- `-r, --reading`: "evangelion" (four Gospels; *default*), "new_testament",
+"old_testament", "bible" (default: "evangelion")
 - `-p, --plain`: Output plain text without formatting or TUI
 - `-f, --formatted`: Output formatted text with ANSI colours (no TUI)
 - `-g, --generate-config`: Generate a default configuration file and exit
@@ -139,7 +143,6 @@ ├── cmd/bibel.go             # Main CLI entry point
 ├── configs/                 # Default configuration files
 │   └── config.example.toml  # The default configuration file
 ├── internal/  
-│   ├── bible/               # Core Bible functionality
 │   ├── config.go            # Reading and writing to config
 │   ├── dateprogression.go   # Date-based position calculation
 │   ├── verse.go             # Data structures

@@ -13,6 +13,7 @@ )
 
 // Args defines the command line arguments
 type Args struct {
+	Reading string `arg:"-r,--reading" help:"reading mode: evangelion (Gospels), new_testament, old_testament, bible (default: evangelion)"`
 	Plain bool `arg:"-p,--plain" help:"output plain text without formatting or TUI"`
 	Formatted bool `arg:"-f,--formatted" help:"output formatted text with ANSI colours (no TUI)"`
 	GenerateConfig bool `arg:"-g,--generate-config" help:"generate a default configuration file and exit"`
@@ -21,8 +22,9 @@ }
 
 // Description returns a description of the program
 func (Args) Description() string {
-	return "Display today's Bible reading from the four Gospels (Matthew, Mark, Luke, John).\n" +
+	return "Display today's Bible reading based on selected reading mode.\n" +
 		"Reads 12 verses per day based on the current date.\n" +
+		"Reading modes: evangelion (four Gospels), new_testament, old_testament, bible\n" +
 		"Configuration file: $XDG_CONFIG_HOME/bibel/config.toml"
 }
 
@@ -48,6 +50,9 @@ os.Exit(1)
 	}
 
 	// Override config with command line arguments
+	if args.Reading != "" {
+		cfg.ReadingMode = args.Reading
+	}
 	if args.Plain {
 		cfg.OutputMode = "plain"
 	} else if args.Formatted {
@@ -68,7 +73,7 @@ os.Exit(1)
 	}
 
 	// Initialise date progression with configured verses per day
-	dateProg := bible.NewDateProgressionWithConfig(bibleData, cfg.DateProgression.VersesPerDay)
+	dateProg := bible.NewDateProgressionWithReadingMode(bibleData, cfg.DateProgression.VersesPerDay, bible.ReadingMode(cfg.ReadingMode))
 
 	// Get current date
 	currentDate := time.Now()
@@ -92,12 +97,12 @@
 	// Handle different output modes
 	switch outputMode {
 	case "plain":
-		formatter := bible.NewFormatterWithConfig(false, cfg.Formatter.HeaderFormat)
+		formatter := bible.NewFormatterWithConfig(bibleData, false, cfg.Formatter.HeaderFormat)
 		// In plain mode, we don't print the header
 		fmt.Println(formatter.ExtractAndFormat(bibleData, todayBookmark))
 		
 	case "formatted":
-		formatter := bible.NewFormatterWithConfig(cfg.Formatter.UseColours, cfg.Formatter.HeaderFormat)
+		formatter := bible.NewFormatterWithConfig(bibleData, cfg.Formatter.UseColours, cfg.Formatter.HeaderFormat)
 		fmt.Println(formatter.FormatHeader(todayBookmark))
 		fmt.Println(formatter.ExtractAndFormat(bibleData, todayBookmark))
 		

@@ -8,6 +8,9 @@
 # Path to Bible data file (relative to executable or absolute path)
 bible_path = "books/pol_nbg.json"
 
+# Reading mode: "evangelion" (four Gospels), "new_testament", "old_testament", "bible"
+reading_mode = "evangelion"
+
 [tui]
   # Whether to show the quit message "Press q to quit..."
   show_quit_message = true

@@ -11,6 +11,8 @@ )
 
 // Config represents the application configuration
 type Config struct {
+	// Reading mode: "evangelion", "new_testament", "old_testament", "bible"
+	ReadingMode string `toml:"reading_mode" mapstructure:"reading_mode"`
 	// Output mode: "tui", "formatted", "plain"
 	OutputMode string `toml:"output_mode" mapstructure:"output_mode"`
 
@@ -60,6 +62,7 @@
 // DefaultConfig returns a configuration with default values
 func DefaultConfig() *Config {
 	cfg := &Config{
+		ReadingMode: "evangelion",
 		OutputMode: "tui",
 		BiblePath:  "books/pol_nbg.json",
 	}
@@ -95,6 +98,7 @@ viper.AddConfigPath(".")
 
 	// Set defaults
 	defaultCfg := DefaultConfig()
+	viper.SetDefault("reading_mode", defaultCfg.ReadingMode)
 	viper.SetDefault("output_mode", defaultCfg.OutputMode)
 	viper.SetDefault("bible_path", defaultCfg.BiblePath)
 	viper.SetDefault("tui.show_quit_message", defaultCfg.TUI.ShowQuitMessage)
@@ -126,6 +130,24 @@ if err := viper.Unmarshal(&cfg); err != nil {
 		return nil, fmt.Errorf("error unmarshalling config: %w", err)
 	}
 
+	// Apply defaults for any empty fields
+	defaultCfg = DefaultConfig()
+	if cfg.ReadingMode == "" {
+		cfg.ReadingMode = defaultCfg.ReadingMode
+	}
+	if cfg.OutputMode == "" {
+		cfg.OutputMode = defaultCfg.OutputMode
+	}
+	if cfg.BiblePath == "" {
+		cfg.BiblePath = defaultCfg.BiblePath
+	}
+	if cfg.TUI.BorderStyle == "" {
+		cfg.TUI.BorderStyle = defaultCfg.TUI.BorderStyle
+	}
+	if cfg.DateProgression.VersesPerDay == 0 {
+		cfg.DateProgression.VersesPerDay = defaultCfg.DateProgression.VersesPerDay
+	}
+
 	// Validate configuration
 	if err := cfg.Validate(); err != nil {
 		return nil, fmt.Errorf("invalid configuration: %w", err)
@@ -137,6 +159,7 @@
 // SaveConfig saves the configuration to file
 func SaveConfig(cfg *Config) error {
 	// Set up viper with current config
+	viper.Set("reading_mode", cfg.ReadingMode)
 	viper.Set("output_mode", cfg.OutputMode)
 	viper.Set("bible_path", cfg.BiblePath)
 	viper.Set("tui.show_quit_message", cfg.TUI.ShowQuitMessage)
@@ -174,6 +197,18 @@ // GetConfigPath returns the path to the configuration file
 
 // Validate checks if configuration values are valid
 func (c *Config) Validate() error {
+	// Validate reading mode
+	validReadingModes := map[string]bool{
+		"evangelion": true,
+		"new_testament": true,
+		"old_testament": true,
+		"bible": true,
+	}
+	// Allow empty reading mode (will use default)
+	if c.ReadingMode != "" && !validReadingModes[c.ReadingMode] {
+		return fmt.Errorf("invalid reading mode: %s, must be one of: evangelion, new_testament, old_testament, bible", c.ReadingMode)
+	}
+
 	// Validate output mode
 	validOutputModes := map[string]bool{
 		"tui":       true,

@@ -9,11 +9,12 @@ // DateProgression handles calculating Bible position based on date
 type DateProgression struct {
 	bible       *Bible
 	versesPerDay int
+	readingMode  ReadingMode
 }
 
 // NewDateProgression creates a new date progression calculator
 func NewDateProgression(bible *Bible) *DateProgression {
-	return &DateProgression{bible: bible, versesPerDay: 12}
+	return &DateProgression{bible: bible, versesPerDay: 12, readingMode: ReadingModeEvangelion}
 }
 
 // NewDateProgressionWithConfig creates a new date progression calculator with config
@@ -21,7 +22,15 @@ func NewDateProgressionWithConfig(bible *Bible, versesPerDay int) *DateProgression {
 	if versesPerDay <= 0 {
 		versesPerDay = 12
 	}
-	return &DateProgression{bible: bible, versesPerDay: versesPerDay}
+	return &DateProgression{bible: bible, versesPerDay: versesPerDay, readingMode: ReadingModeEvangelion}
+}
+
+// NewDateProgressionWithReadingMode creates a new date progression calculator with reading mode
+func NewDateProgressionWithReadingMode(bible *Bible, versesPerDay int, readingMode ReadingMode) *DateProgression {
+	if versesPerDay <= 0 {
+		versesPerDay = 12
+	}
+	return &DateProgression{bible: bible, versesPerDay: versesPerDay, readingMode: readingMode}
 }
 
 // GetPositionForDate calculates the verse range for a given date
@@ -32,14 +41,17 @@
 	// Each day shows configured number of verses
 	targetVerseOffset := (dayOfYear - 1) * dp.versesPerDay // Zero-indexed
 
-	// Walk through Gospels to find the position
+	// Walk through appropriate books based on reading mode
 	return dp.findPositionForOffset(targetVerseOffset)
 }
 
 // findPositionForOffset finds the bookmark for a given cumulative verse offset
 func (dp *DateProgression) findPositionForOffset(offset int) (*Bookmark, error) {
-	// Iterate through books 40-43 (Matthew, Mark, Luke, John)
-	for book := 40; book <= 43; book++ {
+	// Determine which books to iterate through based on reading mode
+	startBook, endBook := dp.getBookRange()
+	
+	// Iterate through books in the range
+	for book := startBook; book <= endBook; book++ {
 		// Find last chapter in this book
 		maxChapter := 0
 		for chapter := 1; ; chapter++ {
@@ -47,6 +59,9 @@ if dp.bible.CountVersesInChapter(book, chapter) == 0 {
 				maxChapter = chapter - 1
 				break
 			}
+		}
+		if maxChapter == 0 {
+			continue // Book has no chapters? Shouldn't happen
 		}
 
 		// Iterate through chapters
@@ -76,10 +91,9 @@ offset -= versesInChapter
 		}
 	}
 
-	// If we've gone through all Gospels and offset is still positive, wrap
-	// around to beginning (start over) Calculate modulo offset within total
-	// Gospel verses
-	totalVerses := dp.GetTotalGospelVerses()
+	// If we've gone through all books and offset is still positive, wrap
+	// around to beginning (start over) Calculate modulo offset within total verses
+	totalVerses := dp.GetTotalVersesForMode()
 	if offset >= 0 {
 		adjustedOffset := offset % totalVerses
 		// Recursively find position for adjusted offset
@@ -89,6 +103,22 @@
 	return nil, fmt.Errorf("could not find position for offset %d", offset)
 }
 
+// getBookRange returns the start and end book numbers for the current reading mode
+func (dp *DateProgression) getBookRange() (startBook, endBook int) {
+	switch dp.readingMode {
+	case ReadingModeEvangelion:
+		return 40, 43 // Matthew, Mark, Luke, John
+	case ReadingModeNewTestament:
+		return 40, 66 // Matthew through Revelation
+	case ReadingModeOldTestament:
+		return 1, 39 // Genesis through Malachi
+	case ReadingModeBible:
+		return 1, 66 // Entire Bible
+	default:
+		return 40, 43 // Default to Evangelion
+	}
+}
+
 // applyLookahead applies the lookahead rule (same as BookmarkManager.AdjustForLookahead)
 func (dp *DateProgression) applyLookahead(bookmark *Bookmark) *Bookmark {
 	versesInChapter := dp.bible.CountVersesInChapter(int(bookmark.Book), bookmark.Chapter)
@@ -108,8 +138,27 @@ // Otherwise return the original bookmark
 	return bookmark
 }
 
+// GetTotalVersesForMode returns the total number of verses for the current reading mode
+func (dp *DateProgression) GetTotalVersesForMode() int {
+	total := 0
+	startBook, endBook := dp.getBookRange()
+	
+	for book := startBook; book <= endBook; book++ {
+		for chapter := 1; ; chapter++ {
+			verses := dp.bible.CountVersesInChapter(book, chapter)
+			if verses == 0 {
+				break
+			}
+			total += verses
+		}
+	}
+	return total
+}
+
 // GetTotalGospelVerses returns the total number of verses in all four Gospels
+// Deprecated: Use GetTotalVersesForMode instead
 func (dp *DateProgression) GetTotalGospelVerses() int {
+	// Calculate Gospels total (books 40-43)
 	total := 0
 	for book := 40; book <= 43; book++ {
 		for chapter := 1; ; chapter++ {

@@ -7,21 +7,24 @@ )
 
 // Formatter handles formatting Bible text for display
 type Formatter struct {
+	bible        *Bible
 	useColours   bool
 	headerFormat string
 }
 
 // NewFormatter creates a new formatter with default settings
-func NewFormatter() *Formatter {
+func NewFormatter(bible *Bible) *Formatter {
 	return &Formatter{
+		bible:        bible,
 		useColours:   true,
-		headerFormat: "{book} {chapter}\nw. {first_verse}-{second_verse}",
+		headerFormat: "{book} {chapter}\nv. {first_verse}-{second_verse}",
 	}
 }
 
 // NewFormatterWithConfig creates a new formatter with configuration
-func NewFormatterWithConfig(useColours bool, headerFormat string) *Formatter {
+func NewFormatterWithConfig(bible *Bible, useColours bool, headerFormat string) *Formatter {
 	return &Formatter{
+		bible:        bible,
 		useColours:   useColours,
 		headerFormat: headerFormat,
 	}
@@ -32,20 +35,23 @@ func (f *Formatter) FormatHeader(bookmark *Bookmark) string {
 	template := f.headerFormat
 	if template == "" {
 		// Fall back to default template
-		template = "{book} {chapter}\nw. {first_verse}-{second_verse}"
+		template = "{book} {chapter}\nv. {first_verse}-{second_verse}"
 	}
-	
+
+	// Get book name from Bible data
+	bookName := f.getBookName(bookmark.Book)
+
 	// Replace template variables
 	result := template
-	result = strings.ReplaceAll(result, "{book}", bookmark.Book.String())
+	result = strings.ReplaceAll(result, "{book}", bookName)
 	result = strings.ReplaceAll(result, "{chapter}", fmt.Sprintf("%d", bookmark.Chapter))
 	result = strings.ReplaceAll(result, "{first_verse}", fmt.Sprintf("%d", bookmark.FirstVerse))
 	result = strings.ReplaceAll(result, "{second_verse}", fmt.Sprintf("%d", bookmark.SecondVerse))
-	
+
 	if !f.useColours {
 		return result
 	}
-	
+
 	// Add ANSI colours - simple implementation
 	// For more advanced templating, we'd need a proper template engine
 	const (
@@ -53,7 +59,7 @@ reset  = "\033[0m"
 		green  = "\033[32m"
 		yellow = "\033[33m"
 	)
-	
+
 	// Simple colouring - book and chapter in green, verse range in yellow
 	lines := strings.Split(result, "\n")
 	if len(lines) >= 1 {
@@ -63,11 +69,24 @@ if len(lines) >= 2 {
 		lines[1] = yellow + lines[1] + reset
 	}
 	result = strings.Join(lines, "\n")
-	
+
 	return result
 }
 
-// FormatHeaderWithTemplate is deprecated - use FormatHeader instead
+// getBookName retrieves the book name from Bible data
+func (f *Formatter) getBookName(book BookIndex) string {
+	// Try to find any verse from this book to get the book name
+	// Start from chapter 1, verse 1 and work forward
+	for chapter := 1; chapter <= 150; chapter++ {
+		for verse := 1; verse <= 200; verse++ {
+			if v, ok := f.bible.GetVerse(int(book), chapter, verse); ok {
+				return v.BookName
+			}
+		}
+	}
+	// If we can't find the book in the data, return a generic name
+	return fmt.Sprintf("Book %d", book)
+} // FormatHeaderWithTemplate is deprecated - use FormatHeader instead
 func (f *Formatter) FormatHeaderWithTemplate(bookmark *Bookmark) string {
 	return f.FormatHeader(bookmark)
 }
@@ -108,4 +127,5 @@ func (f *Formatter) ExtractAndFormatWithHeader(bible *Bible, bookmark *Bookmark) string {
 	header := f.FormatHeader(bookmark)
 	content := f.ExtractAndFormat(bible, bookmark)
 	return header + "\n" + content
-}+}
+

@@ -36,7 +36,7 @@ bibleData:  bibleData,
 		bookmark:   bookmark,
 		outputMode: config.OutputMode,
 		styles:     createStyles(config),
-		formatter:  bible.NewFormatterWithConfig(config.Formatter.UseColours, config.Formatter.HeaderFormat),
+		formatter:  bible.NewFormatterWithConfig(bibleData, config.Formatter.UseColours, config.Formatter.HeaderFormat),
 		config:     config,
 	}
 	return m

@@ -1,5 +1,9 @@
 package bible
 
+import (
+	"fmt"
+)
+
 // Verse represents a single Bible verse
 type Verse struct {
 	BookName string `json:"book_name"`
@@ -17,36 +21,31 @@ FirstVerse int
 	LastVerse  int
 }
 
-// BookIndex represents the four Gospels
+// BookIndex represents Bible book numbers
 type BookIndex int
 
+// BookIndex.String returns the string representation of the book index.
+// Note: The actual book name should be retrieved from Bible data using the Formatter.
+// This is kept for backward compatibility but returns a simple numeric representation.
+func (b BookIndex) String() string {
+	// Return numeric representation - actual book names should come from Bible data
+	return fmt.Sprintf("Book %d", b)
+}
+
+// ReadingMode defines the scope of Bible reading
+type ReadingMode string
+
 const (
-	Matthew BookIndex = iota + 40
-	Mark
-	Luke
-	John
+	ReadingModeEvangelion   ReadingMode = "evangelion"    // Books 40-43 (Matthew, Mark, Luke, John)
+	ReadingModeNewTestament ReadingMode = "new_testament" // Books 40-66
+	ReadingModeOldTestament ReadingMode = "old_testament" // Books 1-39  
+	ReadingModeBible        ReadingMode = "bible"         // Books 1-66
 )
 
-func (b BookIndex) String() string {
-	switch b {
-	case Matthew:
-		return "Ewangelia wg. Mateusza"
-	case Mark:
-		return "Ewangelia wg. Marka"
-	case Luke:
-		return "Ewangelia wg. Łukasza"
-	case John:
-		return "Ewangelia wg. Jana"
-	default:
-		return "Unknown"
-	}
-}
-
 // Bookmark represents the current reading position
 type Bookmark struct {
 	Book        BookIndex `toml:"book"`
 	Chapter     int       `toml:"chapter"`
 	FirstVerse  int       `toml:"first_verse"`
 	SecondVerse int       `toml:"second_verse"`
-}
-
+}