For a great and effectual door is opened to me. He assigns two reasons for remaining for a longer time at Ephesus -- 1st, Because an opportunity is afforded him there of furthering the gospel; and 2dly, Because, in consequence of the great number of adversaries that were there, his presence was particularly required. "I shall do much good by prolonging my stay here for a little while, and were I absent, Satan would do much injury." In the first clause, he makes use of a metaphor that is quite in common use, when he employs the term door as meaning an opportunity. For the Lord opened up a way for him for the furtherance of the gospel. He calls this a great door, because he could gain many. He calls it effectual, inasmuch as the Lord blessed his labor, and rendered his doctrine effectual by the power of His Spirit. We see, then, how this holy man [1] sought everywhere Christ's glory, and did not select a place with a view to his own convenience or his own pleasure; but simply looked to this -- where he might do most good, and serve his Lord with most abundant fruit; and in addition to this, he did not merely not shrink back from hardships, but presented himself, of his own accord, where he saw that he would have to contend more keenly, and with greater difficulty. For the reason why he remained [2] was, that many adversaries were at hand; and the better equipped he was for enduring their assault, he required to be so much the better prepared, and the more resolute.

Footnotes

1 - "Ce sainct Apostre;" -- "This holy Apostle."

2 - "En Ephese;" -- "In Ephesus."

For a great door - There is abundant opportunity for usefulness. The word "door" is used evidently to denote an occasion or an opportunity for doing anything. It is the means by which we have entrance or access; and hence denotes facility in doing anything when there is no obstruction; see Acts 14:27; 2-Corinthians 2:12; Colossians 4:3.
And effectual - That is, effective, or adapted to success; presenting opportunity for great effects. There is abundant opportunity to preach the gospel; there is attention to what is spoken, and great interest in it; there is great encouragement to labor. It is possible that this was one of the reasons why Paul had changed his mind about Macedonia. It would require time to visit Corinth, as he would wish to remain there; and an unexpected opportunity having arisen for doing good, he judged it best to remain at Ephesus as long as practicable, and then to go at once to Macedonia.
And there are many adversaries - Many opposers; many who resist the gospel. These were doubtless in part Jews who excited opposition to him, and in part the friends of Demetrius; see Acts 19. That Paul had great success in Ephesus, and that his labors were attended with a great revival of religion there, is manifest from that chapter. We may remark here:
(1) That such a work of grace, such a setting open a great and effectual door, is often the occasion of increased opposition to the gospel. It is no uncommon thing that the adversaries of Christ should be excited at such times; and we are not to be surprised if the same thing should occur now which occurred in the time of Paul.
(2) this was regarded by Paul as no reason why he should leave Ephesus, but rather as a reason why he should remain there. It was regarded by him as an evidence that the Holy Spirit was there. It was proof that the enemies of God were alarmed, and that the kingdom of Christ was advancing. His presence, also, would be needed there, to encourage and strengthen the young converts who would be attacked and opposed; and he deemed it his duty to remain. A minister should never wish to make enemies to the gospel, nor seek to excite them to make opposition; but such opposition is often evidence that the Spirit of God is among a people; that the consciences of sinners are aroused and alarmed; and that the great enemy of God and man is making, as he was at Ephesus, a desperate effort to preserve his kingdom from being destroyed.
(3) a minister should regard it as his duty in a special manner to be among his people when there is such opposition excited. His presence is needed to comfort and encourage the church; and when the minds of people are excited, it is often the best time to present truth, and to defend successfully the great doctrines of the Bible.
(4) ministers should not be discouraged because there is opposition to the gospel. It is one ground of encouragement. It is an indication of the presence of God in awakening the conscience. And it is far more favorable as a season to do good than a dead calm, and when there is universal stagnation and unconcern.

A great door and effectual is opened - Θυοα γαρ μοι ανεωγε μεγαλη και ενεργης· A great and energetic door is opened to me; that is, God has made a grand opening to me in those parts, which I perceive will require much labor; and besides, I shall have many adversaries to oppose me. So Bp. Pearce understands the words ενεργης, not as signifying effectual, but as implying full of labor. Door often signifies occasion or opportunity; but here, the apostle may allude to the throwing open of the great doors of the Circus Maximus before the chariot races began; and the many adversaries may refer to the numerous competitors in those races.
God gave him a grand opportunity to preach the Gospel; but he was not to expect that either Satan or wicked men would leave him unmolested.

For a great door and (d) effectual is opened unto me, and [there are] many adversaries.
(d) Very fit and convenient to do great things by.

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 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.

door-- (2-Corinthians 2:12). An opening for the extension of the Gospel. Wise men are on the watch for, and avail themselves of, opportunities. So "door of hope," Hosea 2:15. "Door of faith," Acts 14:27. "An open door," Revelation 3:8. "A door of utterance," Colossians 4:3. "Great," that is, extensive. "Effectual," that is, requiring great labors [ESTIUS]; or opportune for effecting great results [BEZA].
many adversaries--who would block up the way and prevent us from entering the open door. Not here false teachers, but open adversaries: both Jews and heathen. After Paul, by his now long-continued labors at Ephesus, had produced effects which threatened the interests of those whose gains were derived from idolatry, "many adversaries" arose (Acts 19:9-23). Where great good is, there evil is sure to start up as its antagonist.

A great door - As to the number of hearers. And effectual - As to the effects wrought upon them. And there are many adversaries - As there must always be where Satan's kingdom shakes. This was another reason for his staying there.