Romans 15:18

For I will not dare to speak of any of those things
He suggests that the false teachers did speak of things which were not done by them at all, and much less were what Christ had done by them; and signifies that he was a conscientious man, and could speak nothing but what was truth; his conscience would not suffer him, nor could he allow himself to make mention of anything, that was not done by him, as if it was; nor of anything that was done by himself, nor of anything that was done, as if it was done by himself, but as it was wrought by Christ; nor had he any need to speak of any other things which he had wrought himself, as he could not of what he had not wrought at all; or, as he says,

which Christ hath not wrought by me:
signifying that what he had wrought, and which he could with good conscience speak of to the honour of Christ, and the glory of his grace, were not wrought by himself, but what Christ wrought by him; he was only the instrument, Christ was the efficient cause: as a Christian, it was not he that lived, but Christ lived in him; as a minister, it was not he that spoke, but Christ spoke in him; nor was it he that laboured, but the grace of Christ that was with him; much less was it he that converted souls, but Christ did it by him:

to make the Gentiles obedient;
the nations of the world, who had been brought up in blindness and ignorance of God, in rebellion and disobedience to him. The Gospel was sent among them, and was blessed unto them, to make them, of disobedient, obedient ones; not to men, but to God; not to magistrates and ministers, though they were taught to be so to both, but to Christ; to him as a priest, by being made willing to be saved by him, and him only, renouncing their own works, and disclaiming all other ways of salvation; and to submit to his righteousness for their justification before God, and acceptance with him; and to deal with his precious blood for pardon and cleansing; to rely on his sacrifice for the atonement of their sins, and to make use of him as the new and living way to the Father, as their one and only mediator, advocate, and intercessor; and to him as a prophet, to the faith of the Gospel, and the doctrines of it; not barely by hearing it, and notionally assenting to it, but by embracing it heartily, and professing it publicly and sincerely; and to him as a King, by owning him as such, and as theirs; and by subjecting to his ordinances, and obeying his commands in faith and fear, and from love to him: the means whereby these persons were brought to the obedience of Christ, and of faith, are

by word and deed;
or "deeds", as the Vulgate Latin, Syriac, and Ethiopic versions read: by the former is meant, the word of the Gospel and the preaching of it, being sent unto them, and coming with power, and not as the word of man, but as the word of God; and by the latter, either the labour of the apostle, the pains he took, the hardships he endured, in ministering: the Gospel to them; or his agreeable life and conversation, which were a means of recommending the word, and of engaging an attention to it; or rather the miraculous works and mighty deeds which were wrought by the apostle, in confirmation of the doctrine he preached, as it seems to be explained in ( Romans 15:19 ) .