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.