For a great door
Meaning an opportunity of ministering the word at Ephesus, a very populous city, and where he might have hope great good would be done. Some think that by this fair opportunity, or hopeful prospect, he means the populousness of the city; others, the conversion of some great men in it, which had made way for the introduction of Gospel there: but it seems rather to intend the desire that there appeared in many persons here to have the Gospel preached unto them; they flocked unto it; their hearts were opened to attend to it, and great numbers believed; and the apostle found a door of utterance in himself, and a door of entrance in them, which were reasons with him to tarry here.
And effectual is opened to me;
not by him, but to him: this door was opened by him who has the key of David, that opens, and no man shuts; and the door of faith being opened by him, it was effectual to the quickening of sinners dead in trespasses and sins, to the enlightening of blind eyes, unstopping of deaf ears, and softening hard hearts; to the turning of souls from the power of Satan to God, to the quickening, comforting, and establishing of saints, and indeed to salvation to all that believe; which is the case when the word comes, not in word only, but in power; then it works effectually in them that believe; and since there was an opportunity of preaching the Gospel with such good effect, the apostle was desirous of making use of it:
and there are many adversaries;
as there always are where the Gospel is preached, and especially with success, when sinners are converted, and saints are edified and comforted. The adversary Satan roars, and the posse of devils under him are employed one way or another to obstruct the Gospel if possible; false teachers are raised up to oppose it, and profane men are instigated by him to persecute the preachers and professors of it: so it was at Ephesus, the Jews disputed against it, and spoke evil of it; Demetrius the silversmith, and those of his craft, rose up in a tumultuous manner, crying, great is Diana of the Ephesians, stirring up the people against the apostle, and his companions; all which he had some foreviews of, and found to be true by experience, as may be seen in ( Acts 19:21-41 ) and which, though to another man would have been a reason to have departed, was a reason with him to stay; to bear his testimony to the Gospel, to appear in the defence of it, against the disputers of this world, and to strengthen and establish the minds of weak believers in it, who might have been in some danger through so many adversaries; wherefore he saw and judged that his presence was necessary, and that it was proper for him to stay the time he mentions.