A friend of mine who is a pastor was contacted by a man in the Philippines who was seeking discipleship. As the two have developed a relationship the following question arose. This was my initial answer to assist my friend’s response.
If the Bible teaches that only men are to be pastors, why then do ministries under women often prosper?
Why do unorthodox churches seem to prosper from a worldly perspective?
Why does the church down the road that does preach the Gospel but whose form of church government is not Biblical become flooded with people?
How is it that someone is converted under an unregenerate minister who happens to state the Gospel?
How can it be that a Gospel-centred church that appears to abide by New Testament principles not grow, or even perhaps shrink under persecution?
Some of these questions relate to God’s providence, which can sometimes be mysterious.
Returning to the original question, I would say that because complementarianism vs. egalitarianism is a secondary matter and that above all else the Lord desires people to be saved (primary issue) the Lord at times works through unorthodox means. Complementarians must also remember that some female pastors are sisters in Christ (just like some female [and male!] pastors are not). I think the best example to answer this questions is found in Judges.
Formal positions of leadership in Israel were always male. The case of Deborah (Judges 4:4) appears to be an unusual exception. It appears to be an exception until one sees that Old Covenant prophetess does not equal New Covenant pastor. It appears an exception until “to judge” (which literally means defend) is coupled with her role as prophetess (a woman, in this case, who spoke the word of God, often to people in formal positions of power). In summoning Barak she shows she is not indeed the formal leader in the sense that he is, otherwise she would not have told him to gather the troops (v. 6b). We further see their mutual-leadership in the song of Judges 5. Though Barak ultimately went out into battle he did not get the glory, not because he relied on a woman (the Lord spoke through her!) but because he did not assume the role of faith and leadership that he should have (v. 9). As a result the glory of the victory was given to Jael who the Lord used to kill the enemy leader Sisera. The Lord used two faithful women (in this case) who stepped up in the absence of a faithful man, instead of the faithless man, because the Lord’s ultimate aim was deliverance from Israel’s enemies.
This question and the story of Deborah and Barak reminds me of Ezk 20:30, “And I sought for a man among them, that should build up the wall, and stand in the gap [of the wall] before me for the land, that I should not destroy it; but I found none.” The Lord is using many sisters in Christ today to accomplish salvation because Christian men are not standing up to the positions of leadership in the home, church and society that God calls them to.
Correct gender roles are not about capability but faithfulness to design. When this is not heeded, it doesn’t mean the Lord won’t use a woman when she steps up into the role of a man, even if this is not the Lord’s ultimate design. Why? Ultimately men and women are called to be faithful to the Lord’s purposes in gender, but because salvation is His ultimate end, He will not stop at this even if this means using a woman and giving the glory to her instead of the man to whom (in this case) it would normally rightfully belong.
The Lord’s Sweetest Blessings,
 That men and women are equal before God but created for complementary roles.
 That men and women are equal in ALL things.
 See: http://www.adfontes.ca/posts/post/article/deborah-and-the-defeater-verses/index.php. I believe Paul is spot on here.
 Godly men would do well to listen to the counsel of godly and respectful women. I have listened and am the wiser for it. They have spoken and have contributed to the work of the body (in my case part of the head).