The Apostle Paul
Romans 14:23ESV·traditional attribution

But whoever has doubts is condemned if he eats, because the eating is not from faith. For whatever does not proceed from faith is sin.

John Calvin Reformed @genevareformer

23. But he who is undecided, etc. He very fitly expresses in one word the character of that mind which vacillates and is uncertain as to what ought to be done; for he who is undecided undergoes alternate changes, and in the midst of his various deliberations is held suspended by uncertainty.

Matthew Henry Presbyterian @wholebiblehenry

We have in this chapter, I. An account of the unhappy contention which had broken out in the Christian church. Our Master had foretold that offences would come; and, it seems, so they did, for want of that wisdom and love which would have prevented discord, and kept up union among them. 1.

Commenting on Romans 14:1-23

Albert Barnes Presbyterian @notesbybarnes

Verse 23. He that doubteth, he that is not fully satisfied in his mind; who does not do it with a clear conscience. The margin has it rendered correctly, "He that discerneth and putteth a difference between meats." He that conscientiously believes, as the Jew did, that the Levitical law respecting the difference between meats was binding on Christians. Is damned.