Clearly, Paul addresses members of the Corinthian Church in much of 1 Corinthians 3, using the word you 11 times in verses 1-9 and 8 times in verses 16-23. But starting in verse 10 and continuing through verse 15, he switches abruptly from referring specifically to Corinthian Church members through the term you to seemingly referring generally to everyone through the terms he, himself, another, each man, no man, and any man. No clear reference to only Corinthian Church members occurs in 1 Corinthians 3:10-15 through the word you or in any other obvious way.
“According to the grace of God which was given to me, like a wise master builder I laid a foundation, and another is building on it. But each man must be careful how he builds on it. For no man can lay a foundation other than the one which is laid, which is Jesus Christ. Now if any man builds on the foundation with gold, silver, precious stones, wood, hay, straw, each man’s work will become evident; for the day will show it because it is to be revealed with fire, and the fire itself will test the quality of each man’s work. If any man’s work which he has built on it remains, he will receive a reward. If any man’s work is burned up, he will suffer loss; but he himself will be saved, yet so as through fire.”
That oddity suggests Paul meant to generalize from his specific message to the Christian members of the Corinthian Church to everyone, no matter what their religion or lack thereof.
If that was indeed his intention, then it would seem Paul is here saying that all will be saved, yet so as through fire for some, i.e., those metaphorically represented in 1 Corinthians 3 as God’s building constructed with faulty material.
Why else would Paul have so abruptly changed, twice, the apparent, addressed group from you in verses 1-9, to other than you in verses 10-15, then back again to you in verses 16-23?