As I can see it, there are a few key dangers when it comes to pastors getting a PhD.
1) Big Head Syndrome. It seems quite possible that a pastor who does get a PhD could think himself better than those of his congregation who do not have PhDs. That would be a terrible thing, because it would mean that the pastor was despising his congregation. A pastor must always cultivate a heart of love for his people and must see himself as one of them and in no way better than them. So any pastor who sets out to get a PhD must decide from the start that he will be vigilant about fighting the pride of his heart. He must constantly remind himself that letters after his name signify intellectual training, not spiritual or social stature. The pastor with a PhD is not a super-Christian. He is just a man with a degree.
2) Detachment from the everyday. One reason Christians have sometimes derided educated people is the tendency of such people to be detached from everyday life. This is a potential pitfall for any intellectual, but it is particularly damning for a pastor. A pastor is by the nature of his work one who is in tune with the needs of his people, many of whom will not be intellectuals. He must show that he can speak to them and reach them on their level. He must avoid treating every sermon or teaching time as if it is a scholar’s society meeting. He must constantly watch himself to make sure that, though he undertake rigorous intellectual work, he stays in close contact with his people, the sheep of his flock.
So there are a couple of dangers that pastors will need to watch out for. I’m sure that there are others one can think of, but these two certainly cover a good deal of the dangerous ground that pastors with PhDs must carefully avoid. We should also note that these two dangers will to some extent apply not only to pastors with PhDs, but to all Christians. We are not an elitist people, and we do not view one another as the world does, according to status conferred by degrees, heritage, or even talent.