The Lord Jesus Christ Himself says I will never leave you nor forsake you. A person may quit on the Lord but the Lord will never quit on them.
i will leave those people who hold to OSAS with this:
Romans 11:19-24
19 You will say then, “Branches were broken off that I might be grafted in.”
20 Well said. Because of unbelief they were broken off, and you stand by faith. Do not be haughty, but fear.
21 For if God did not spare the natural branches, He may not spare you either.
22 Therefore consider the goodness and severity of God: on those who fell, severity; but toward you, goodness, if you continue in His goodness. Otherwise you also will be cut off.
23 And they also, if they do not continue in unbelief, will be grafted in, for God is able to graft them in again.
24 For if you were cut out of the olive tree which is wild by nature, and were grafted contrary to nature into a cultivated olive tree, how much more will these, who are natural branches, be grafted into their own olive tree?
Ezekiel 18:21-32
21 “But if a wicked man turns from all his sins which he has committed, keeps all My statutes, and does what is lawful and right, he shall surely live; he shall not die.
22 None of the transgressions which he has committed shall be remembered against him; because of the righteousness which he has done, he shall live.
23 Do I have any pleasure at all that the wicked should die?” says the Lord God, “and not that he should turn from his ways and live?
24 “But when a righteous man turns away from his righteousness and commits iniquity, and does according to all the abominations that the wicked man does, shall he live? All the righteousness which he has done shall not be remembered; because of the unfaithfulness of which he is guilty and the sin which he has committed, because of them he shall die.
25 “Yet you say, ‘The way of the Lord is not fair.’ Hear now, O house of Israel, is it not My way which is fair, and your ways which are not fair?
26 When a righteous man turns away from his righteousness, commits iniquity, and dies in it, it is because of the iniquity which he has done that he dies.
27 Again, when a wicked man turns away from the wickedness which he committed, and does what is lawful and right, he preserves himself alive.
28 Because he considers and turns away from all the transgressions which he committed, he shall surely live; he shall not die.
29 Yet the house of Israel says, ‘The way of the Lord is not fair.’ O house of Israel, is it not My ways which are fair, and your ways which are not fair?
30 “Therefore I will judge you, O house of Israel, every one according to his ways,” says the Lord God. “Repent, and turn from all your transgressions, so that iniquity will not be your ruin.
31 Cast away from you all the transgressions which you have committed, and get yourselves a new heart and a new spirit. For why should you die, O house of Israel?
32 For I have no pleasure in the death of one who dies,” says the Lord God. “Therefore turn and live!”
2 Timothy 2:11-13
11 This is a faithful saying:
For if we died with Him,
We shall also live with Him.
12 If we endure,
We shall also reign with Him.
If we deny Him,
He also will deny us.
13 If we are faithless,
He remains faithful;
He cannot deny Himself.
OSAS/Perseverance of the Saints is Gnosticism. nothing more.