The Old Testament uses the term "backsliding" to speak of those who have been near to God but have allowed sin to take them away from Him.
The prophet Jeremiah said, "Our backsliding is great; we have sinned against you" (Jeremiah 14:7). Backsliding in Scripture is always seen as a very serious matter: "'Your wickedness will punish you; your backsliding will rebuke you. Consider then and realize how evil and bitter it is for you when you forsake the Lord your God and have no awe of me,' declares the Lord, the Lord Almighty" (Jeremiah 2:19, NIV).
Backsliding can be caused by many things. However, whatever the sin might be that leads us away from God, it must be dealt with honestly and brought before Him in repentance. God loves us and wants us to be close to Him. Even when we sin against Him, He promises to forgive. "I will heal their waywardness and love them freely, for my anger has turned away from them" (Hosea 14:4).
We must always fight against backsliding, but if we do backslide, we know that when we renounce our sin and return to God, there is forgiveness and reconciliation. The Bible says, "If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness" (1 John 1:9).