There is assurance and power for all whose heart is to continue with him. These scriptures affirm that He will also work in us to bring us home. However they do not address the case of a person who is in rebellion or who is rejecting the faith.
Paul's views on ultimate salvation are explained in Colossians 1:21-22.
First Paul identifies those he is writing to those who were unbelievers in the past
21 And you, who once were alienated and hostile in mind, doing evil deeds
Then he describes their present state as believers
22 he has now reconciled in his body of flesh by his death,
Next he lays out God's purpose and plan for them in the future:
22...in order to present you holy and blameless and above reproach before him,
If the passage stopped here the doctrine of OSAS would remain intact but Paul adds conditions which must be met if they are to receive the promised reward:
23 IF indeed you continue in the faith, stable and steadfast, not shifting from the hope of the gospel that you heard, which has been proclaimed in all creation under heaven, and of which I, Paul, became a minister.
Paul says that in order to reach the promised reward we must continue in the faith. Let us look at the opposite choice. What if instead of meeting this condition we abandon our faith and deny the truth of the gospel? What happens then? Well, according to this verse we will NOT be among those who will be presented before him holy and unblamable, prepared for eternal fellowship.
Paul’s teaching about salvation plainly disagrees with the OSAS axiom that everyone who starts with Christ will inevitably continue to the end.
You're just another sad and classic example of one who confuses salvation which is a gift (Ephesians 2:8-9 KJV) with reward which if built on the foundation a wise master builder Paul laid is gold, silver, precious stones and if not: wood, hay, stubble. Take note~ whether gold,silver, precious stones, wood, hay stubble: still SAVED!
1 Corinthians 3:10 According to the grace of God which is given unto me, as a wise masterbuilder, I have laid the foundation, and another buildeth thereon. But let every man take heed how he buildeth thereupon.
1 Corinthians 3:11 For other foundation can no man lay than that is laid, which is Jesus Christ.
1 Corinthians 3:12 Now if any man build upon this foundation gold, silver, precious stones, wood, hay, stubble;
1 Corinthians 3:13 Every man's work shall be made manifest: for the day shall declare it, because it shall be revealed by fire; and the fire shall try every man's work of what sort it is.
1 Corinthians 3:14 If any man's work abide which he hath built thereupon, he shall receive a reward.
1 Corinthians 3:15 If any man's work shall be burned, he shall suffer loss: but he himself shall be saved; yet so as by fire.