"Seek ye the LORD while he may be found, call ye upon him while he is near: Let the wicked forsake his
way (that's your part), and the unrighteous man his thoughts (that's
your part): and let him return unto the LORD (that's your part), and he will have mercy upon him; and to our God, for he will abundantly pardon.
(that's God's part)"
"The backslider in heart shall be filled with his own ways: and a good man shall be satisfied from himself."
"Now the just shall live by faith: but if any man draw back, my soul shall have no pleasure in him. But we are not of them who draw back unto perdition; but of them that believe to the saving of the soul."
"For if after they have escaped the pollutions of the world through the knowledge of the Lord and Saviour Jesus Christ, they are again entangled therein, and overcome, the latter end is worse with them than the beginning. For it had been better for them not to have known the way of righteousness, than, after they have known it, to turn from the holy commandment delivered unto them. But it is happened unto them according to the true proverb, The dog is turned to his own vomit again; and the sow that was washed to her wallowing in the mire."
(2 Peter 2:20-22)
Nevertheless, when the backslider submits to God, you find that there is hope
for the backslider,
"Go and proclaim these words toward the north, and say, Return, thou backsliding Israel, saith the LORD; and I will not cause mine anger to fall upon you: for I am merciful, saith the LORD, and I will not keep anger for ever. Only acknowledge thine iniquity, that thou hast transgressed against the LORD thy God, and hast scattered thy ways to the strangers under every green tree, and ye have not obeyed my voice, saith the LORD. Turn, O backsliding children, saith the LORD; for I am married unto you: and I will take you one of a city, and two of a family, and I will bring you to Zion:"
"And he said, A certain man had two sons: And the younger of them said to his father, Father, give me the portion of goods that falleth to me. And he divided unto them his living. And not many days after the younger son gathered all together, and took his journey into a far country, and there wasted his substance with riotous living. And when he had spent all, there arose a mighty famine in that land; and he began to be in want. And he went and joined himself to a citizen of that country; and he sent him into his fields to feed swine. And he would fain have filled his belly with the husks that the swine did eat: and no man gave unto him. And when he came to himself, he said, How many hired servants of my father's have bread enough and to spare, and I perish with hunger! I will arise and go to my father, and will say unto him, Father, I have sinned against heaven, and before thee, And am no more worthy to be called thy son: make me as one of thy hired servants. And he arose, and came to his father. But when he was yet a great way off, his father saw him, and had compassion, and ran, and fell on his neck, and kissed him. And the son said unto him, Father, I have sinned against heaven, and in thy sight, and am no more worthy to be called thy son. But the father said to his servants, Bring forth the best robe, and put it on him; and put a ring on his hand, and shoes on his feet: And bring hither the fatted calf, and kill it; and let us eat, and be merry: For this my son was dead, and is alive again; he was lost, and is found. And they began to be merry. Now his elder son was in the field: and as he came and drew nigh to the house, he heard musick and dancing. And he called one of the servants, and asked what these things meant. And he said unto him, Thy brother is come; and thy father hath killed the fatted calf, because he hath received him safe and sound. And he was angry, and would not go in: therefore came his father out, and intreated him. And he answering said to his father, Lo, these many years do I serve thee, neither transgressed I at any time thy commandment: and yet thou never gavest me a kid, that I might make merry with my friends: But as soon as this thy son was come, which hath devoured thy living with harlots, thou hast killed for him the fatted calf. And he said unto him, Son, thou art ever with me, and all that I have is thine. It was meet that we should make merry, and be glad: for this thy brother was dead, and is alive again; and was lost, and is found."