How do we know that repentance is essential for Christians?

The necessity of repentance is emphasized throughout Scripture, rooted in the concept that true conversion involves a change of heart and direction towards God. Peter's experience post-denial illustrates this principle vividly; after denying Christ, he wept bitterly, a sign of his genuine remorse. Jesus later reinstated him, emphasizing that true repentance not only involves acknowledgment of sin but also a commitment to follow Christ faithfully thereafter. This model demonstrates that Christians, despite their failures, can approach God for mercy and find restoration, reflecting the promise found in 1 John 1:9, that if we confess our sins, He is faithful and just to forgive us.