Albert Barnes Commentary 1 Corinthians 15:31

"I protest by that glorifying in you, brethren, which I have in Christ Jesus our Lord, I die daily." — 1 Corinthians 15:31 (ASV)

I protest. This is a term used in swearing an oath and denotes a strong asseveration. The subject was important; it deeply interested his feelings, and he makes a strong protestation regarding it. Compare John 3:5. "I solemnly affirm, or declare."

By your rejoicing. Many manuscripts here read "by our rejoicing," but the correct reading is undoubtedly that which is in the present Greek text, "by your rejoicing." The meaning of the phrase, which all admit to be obscure, is probably, "I protest, or solemnly declare by the glorying or exultation which I have on your account; by all my ground of glorying in you; by all the confident boasting and expectation which I have of your salvation."

He hoped for their salvation. He had labored for that. He had boasted of it and confidently believed that they would be saved.

Regarding that as safe and certain, he says it was just as certain that he died daily on account of the hope and belief of the resurrection. "By our hopes and joys as Christians; by our dearest expectations and grounds of confidence, I swear, or solemnly declare, that I die daily."

Men swear or affirm by their objects of dearest affection and desire; and the meaning here is, "So certainly as I confidently expect your salvation, and so certainly as we look to eternal life, so certain is it that I am constantly exposed to die and suffer that which may be called a daily death?"

Which I have in Christ Jesus. This refers to the rejoicing, boasting, or glorying in regard to you which I am permitted to cherish through the grace and favor of the Savior. His boasting, or confident expectation concerning the Corinthians, he enjoyed only by the mercy of the Lord Jesus, and he delighted to trace it to Him.

I die daily. Compare Romans 8:36. I endure so many sufferings and persecutions that it may be called a daily dying. I am constantly in danger of my life, and my sufferings each day are equal to the pains of death.

Paul probably referred here particularly to the perils and trials he then endured at Ephesus. His object was to impress their minds with the firmness of his belief in the certainty of the resurrection, for which he suffered so much, and to show them that all their hopes also rested on this doctrine.