Falling back into sin and away from God is backsliding.
1 John 2:1 My little children, these things write I unto you, that ye sin not. And if any man sin, we have an advocate with the Father, Jesus Christ the righteous: Revelation 2:4,5 002:004 Nevertheless I have somewhat against thee, because thou hast left thy first love. 002:005Remember therefore from whence thou art fallen, and repent, and do the first works; or else I will come unto thee quickly, and will remove thy candlestick out of his place, except thou repent. Hebrews 3:12,13 003:012 Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God. 003:013But exhort one another daily, while it is called To day; lest any of you be hardened through the deceitfulness of sin But through God's loving grace and his compassion and mercy we are able to return to him. 1 John 1:9 If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness. Hebrews 8:12 For I will be merciful to their unrighteousness, and their sins and their iniquities will I remember no more. Proverbs 28:13 He that covereth his sins shall not prosper: but whoso confesseth and forsaketh them shall have mercy. John 15:6 If a man abide not in me, he is cast forth as a branch, and is withered; and men gather them, and cast them into the fire, and they are burned. Isaiah 55:7 Let the wicked forsake his way, and the unrighteous man his thoughts: and let him return unto the LORD, and he will have mercy upon him; and to our God, for he will abundantly pardon. Hosea 14:4 I will heal their backsliding, I will love them freely: for mine anger is turned away from him Hebrews 7:25 Wherefore he is able also to save them to the uttermost that come unto God by him, seeing he ever liveth to make intercession for them. 2 Chr. 30:9 For if ye turn again unto the LORD, your brethren and your children shall find compassion before them that lead them captive, so that they shall come again into this land: for the LORD your God is gracious and merciful, and will not turn away his face from you, if ye return unto him.