It also speaks of in the latter times some shall depart from the faith,
As far as unbelief goes Hebrews warns
Heb 3:12 Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God.
And in respects to unbelief here Paul says,
Romans 11:22 Behold therefore the goodness and severity of God: on them which fell, severity; but toward thee, goodness, if thou continue in his goodness: otherwise thou also shalt be cut off.
David to Solomon about the LORD casting off forever those who forsake him.
1 Ch 28:9 And thou, Solomon my son, know thou the God of thy father, and serve him with a perfect heart and with a willing mind:
for the LORD searcheth all hearts, and understandeth all the imaginations of the thoughts: if thou seek him, he will be found of thee;
but if thou forsake him, he will cast thee off for ever.
Again, he that searches the hearts, and so it says, "take heed" here in this instance concerning a heart of unbelief
Heb 3:12 Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God.
Jesus does say these believe for awhile
Luke 8:13 They on the rock are they, which, when they hear, receive the word with joy; and these have no root, which for a while believe, and in time of temptation fall away.
And you can back up and bring in the root in Romans also, and see the unbelief there also
Romans 11;7 And if some of the branches be broken off, and thou, being a wild olive tree, wert graffed in among them, and with them partakest of the root and fatness of the olive tree;
Romans 11:18 Boast not against the branches. But if thou boast, thou bearest not the root, but the root thee.
Romans 11:19 Thou wilt say then, The branches were broken off, that I might be graffed in.
Romans 11:20 Well; because of unbelief they were broken off, and thou standest by faith. Be not highminded, but fear:
Romans 11:21 For if God spared not the natural branches, take heed lest he also spare not thee.
I've seen Atheists repent in tears and become the strongest believers I've ever seen.
I've never seen a OSAS believer change his mind.
I'm sure it's happened somewhere, but I have personally never seen it.

