What does the Bible say about unbelief and faith?

The Bible emphasizes the importance of faith over unbelief, particularly as seen in the case of Zacharias in Luke 1. When the angel Gabriel announces to Zacharias that he will have a son, Zacharias responds with doubt, asking, 'whereby shall I know this?' This reflects a common human condition—unbelief. Yet, faith is shown to be the response God desires. Romans 4:20-21 urges believers to be fully persuaded that what God has promised, He is able to perform, encouraging an unwavering trust in God's Word. Faith leads to the acknowledgment of God's supreme power and goodness.