The Apostle Paul
2 Corinthians 6:18BSB·traditional attribution

And: “I will be a Father to you, and you will be My sons and daughters, says the Lord Almighty.”

John Calvin Reformed @genevareformer

18. I will be a Father unto you. This promise does not occur in one passage merely, but is repeated in various instances. Paul has added it with this view, that a recognition of the great honor to which God has exalted us, might be a motive to stir us up to a more ardent desire for holiness.

Matthew Henry Presbyterian @wholebiblehenry

The apostle proceeds to address himself more particularly to the Corinthians, and cautions them against mingling with unbelievers. Here observe, I. How the caution is introduced with a profession, in a very pathetic manner, of the most tender affection to them, even like that of a father to his children, Co2 6:11-13.

Commenting on 2 Corinthians 6:11-18

Albert Barnes Presbyterian @notesbybarnes

Verse 18. And will be a Father unto you. A father is the protector, counsellor, and guide of his children, he instructs them, provides for them, and counsels them in time of perplexity. No relation is more tender than this. In accordance with this, God says, that he will be to his people their Protector, Counsellor, Guide, and Friend.