How does sin affect a believer's relationship with God?

Sin creates a barrier in the believer's relationship with God, leading to feelings of guilt and separation. David's mourning for Abner in 2 Samuel 3 exemplifies the sorrow that accompanies sin, reflecting how God desires repentance and reconciliation. When believers stray, they are called to confess their sins, as 1 John 1:9 assures us that 'if we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.' Thus, understanding the weight of sin encourages believers to seek restoration through God's grace and mercy.