John Calvin Commentary Romans 1:4

"who was declared [to be] the Son of God with power, according to the spirit of holiness, by the resurrection from the dead; [even] Jesus Christ our Lord," — Romans 1:4 (ASV)

Declared the Son of God, etc.: or, if you prefer, determined (definitus); as if he had said that the power by which he was raised from the dead was something like a decree by which he was proclaimed the Son of God, according to what is said in Psalm 2:7, “I have this day begotten thee.” For this begetting refers to what was made known.

Although some indeed find here three separate evidences of Christ’s divinity—“power” (understanding this to mean miracles), then the testimony of the Spirit, and, lastly, the resurrection from the dead—I still prefer to connect them together and to reduce these three things to one, in this manner: Christ was declared the Son of God by openly exercising a real celestial power, that is, the power of the Spirit, when he rose from the dead. But this power is comprehended when a conviction of it is imprinted on our hearts by the same Spirit.

The Apostle’s language agrees well with this view, for he says that Christ was declared by power, because power peculiar to God shone forth in him and uncontestably proved him to be God; and this was indeed made evident by his resurrection.

Paul says the same thing in another place: having stated that by death the weakness of the flesh appeared, he at the same time extols the power of the Spirit in his resurrection (2 Corinthians 13:4). This glory, however, is not made known to us until the same Spirit imprints a conviction of it on our hearts.

And that Paul includes, together with the wonderful energy of the Spirit which Christ manifested by rising from the dead, the testimony which all the faithful feel in their hearts, is also evident from this: he expressly calls it the Spirit of Holiness. It is as if he had said that the Spirit, insofar as it sanctifies, confirms and ratifies that evidence of its power which it once exhibited.

For Scripture often ascribes such titles to the Spirit as tend to illustrate our present subject. Thus, He is called by our Lord the Spirit of Truth, on account of the effect which he mentions (John 14:17).

Besides, a divine power is said to have shone forth in the resurrection of Christ for this reason—because he rose by his own power, as he had often testified:

“Destroy this temple, and in three days
I will raise it up again,” (John 2:19).

“No man taketh it from me,” etc. (John 10:18).

For he gained victory over death (to which he yielded with regard to the weakness of the flesh,) not by aid sought from another, but by the celestial operation of his own Spirit.