John Calvin Commentary Romans 15:18

"For I will not dare to speak of any things save those which Christ wrought through me, for the obedience of the Gentiles, by word and deed," — Romans 15:18 (ASV)

In order to make the Gentiles obedient, etc. These words prove what his objective was: namely, to make his ministry approved by the Romans, so that his doctrine would not be without fruit. He then proves by evidence that God, by the presence of His power, had given a testimony to his preaching and, in a way, sealed his apostleship, so that no one should have doubted that he was appointed and sent by the Lord.

The evidence consisted of word, work, and miracles. It therefore appears that the term work includes more than miracles. He finally concludes with this expression, through the power of the Spirit; by which he indicates that these things could not have been done without the Spirit as their author.

In short, he declares that regarding both his teaching and his actions, he possessed such strength and energy in preaching Christ that it was clearly the wonderful power of God. Miracles were also added, which were seals to make the evidence more certain.

He mentions word and work first, and then he states one kind of work, namely, the power of performing miracles. Luke observes the same order when he says that Christ was mighty in word and work (Luke 24:19). And John says that Christ referred the Jews to His own works as a testimony of His divinity (John 5:36). Nor does he simply mention miracles, but gives them two designations. But instead of what he says here, the power of signs and of wonders, Peter has miracles and signs and wonders (Acts 2:22). And undoubtedly, they were testimonies of divine power to awaken people, so that, being struck with God’s power, they might admire and at the same time adore Him. Nor are they without a special meaning, but are intended to stimulate us so that we may understand what God is.

This is a striking passage regarding the benefit of miracles: they are designed to prepare people to reverence and obey God. So you read in Mark that the Lord confirmed the truth by the signs which followed (Mark 16:20). Luke declares in Acts that the Lord, by miracles, gave testimony to the word of his grace (Acts 14:3). It is then evident that those miracles which bring glory to creatures and not to God, and which secure credit for lies and not for God’s word, are from the devil. The power of the Spirit, which he mentions in the third place, I apply to both the preceding clauses.