The Apostle Paul
Colossians 1:23BSB·traditional attribution

if indeed you continue in your faith, established and firm, not moved from the hope of the gospel you heard, which has been proclaimed to every creature under heaven, and of which I, Paul, have become a servant.

John Calvin Reformed @genevareformer

23. If ye continue. Here we have an exhortation to perseverance, by which he admonishes them that all the grace that had been conferred upon them hitherto would be vain, unless they persevered in the purity of the gospel. And thus he intimates, that they are still only making progress, and have not yet reached the goal.

Matthew Henry Presbyterian @wholebiblehenry

Here is a summary of the doctrine of the gospel concerning the great work of our redemption by Christ. It comes in here not as the matter of a sermon, but as the matter of a thanksgiving; for our salvation by Christ furnishes us with abundant matter of thanksgiving in every view of it: Giving thanks unto the Father, Col 1:12.

Commenting on Colossians 1:12-29

John Gill Reformed Baptist @doctorgill

If ye continue in the faith,.... In the doctrine of faith which they had received and embraced; and in the grace of faith, and the exercise of it which was implanted in them; and in the profession of faith which they had made: not that the virtue and efficacy of Christ's blood, sufferings, and death, and reconciliation of their persons to God thereby, depended upon...