Why do people not believe in God?

The reasons for unbelief are diverse and deeply rooted in the human heart. According to John 8:44, those who refuse to believe are described as being 'of your father the devil,' indicating that their rejection stems from their origin and sinful nature. Additionally, Romans 1:18-21 explains that people actively suppress the truth of God in unrighteousness. Their refusal to acknowledge God often stems from a love of darkness rather than light, as stated in John 3:19. Belief is not merely a passive condition; it requires a response to God's revelation of Himself, which many choose to reject.