Explain the 'if' in 1 Corinthians 15:1-2 NASB.
1Now I make known to you, brethren, the gospel which I preached to you, which also you received, in which also you stand, 2by which also you are saved, if you hold fast the word which I preached to you, unless you believed in vain." (1 Corinthians 15:1-2 NASB bold and underline mine)
The condition for being presently saved is IF you are presently holding fast the word. ('Hold fast' is the same Greek word Jesus uses to describe the fourth type of soil in Luke 8:15 NASB that retained the word of God and brought it to fruition).
Calvinism says this holding fast the word in faith is the
sign that you truly believe and so you are, therefore, truly saved (as opposed to being a fake believer who shows he's a fake believer because he doesn't continue in the word and bear fruit). Calvinism asserts that the one who truly believes will always believe and so will always be saved. That's why it says perseverance in believing shows one to be truly believing and, therefore, truly saved. But there's always the potential of tomorrow's failure of faith to show that what you thought was true believing today really was not. But let's not go there now.
Non-OSAS doctrine says this holding fast the word is not just the sign one is saved but is the
condition one must satisfy for being presently saved. It says that because of the conditional 'if' Paul uses in the passage. Which is the same 'if' of factual certainty that he uses in the Colossians 1:23 NASB verse you cited. The point being, the fact that, both, the Corinthians and the Colossians are in fact satisfying the condition of the 'if' for being saved and for being able to be presented holy before the Lord has no bearing on the fact that the condition of the 'if'
still has to be met in order to attain what the satisfied condition secures. Stop satisfying the condition for present salvation and you are no longer presently saved. As long as you are presently trusting in Christ you are satisfying the condition for salvation and are secure in the promise of eternal life.
Freegrace doctrine says.....well, it doesn't say anything other than to make the passage not mean what it says. It casts the passage off by insisting that present believing is
not necessary to be presently saved, which completely contradicts the passage. They say there are no 'ifs' for remaining saved once you are saved. It says you can even curse Christ and turn to Islam and you still have the eternal life you received when you first believed.