Once upon a time David married Bathsheba. This marriage was contrary to the will of God and was a sin to have entered into.
But the marriage, once in place, was always counted as a legitimate marriage after that, and in fact the offspring from that marriage became the next king of Israel.
A marriage, even if wrongly entered into, is still a marriage. A divorce, even from a marriage wrongly entered into, is still hated by God.
However, a divorce does, in fact, end a marriage so that is is no longer a marriage. This is shown by the answer Jesus gave the woman at the well, for she said "I have no husband" and Jesus told her she was telling the truth. And this was the truth although she had been married five times and he whom she now had was not her husband.
Given all this, any past history of marriage and divorce clearly should not count against a present candidate for the ministry, providing his life indicates he has repented of previous sins of divorce and remarriage (and all the other sins in his life also, of course) and his current marital status qualifies, that is, he doesn't have more than one wife.
On the other hand, I have a fear that we do very little in the way of actually examining a candidate in terms of the moral standards; Jesus had a lot to say against the pharasees that did not at all involve divorce, but do we ever judge a man on those things Jesus complained about in them?