How does the Bible define a holy nation?

The term 'holy nation' in 1 Peter 2:9 indicates that believers collectively embody the character of God’s holiness. This means they are called to live in a manner that reflects God's attributes to the world around them. As a holy nation, they have been set apart from sin and darkness, making them distinct in their conduct and witness. The call to holiness encourages believers to pursue a lifestyle that honors God and reveals His glory, fulfilling their mission to declare the excellencies of Him who called them out of darkness into His marvelous light.