In one of Paul’s letters, he wrote, “Now a bishop must be above reproach, the husband of one wife” (1 Tim 3:2). Some non-Catholic Christians try to use this as proof that bishops should be married. However, that is not in fact what Paul is trying to say. Here is the passage again, this time in context:
1 Tim 3:1-5 The saying is sure: If any one aspires to the office of bishop, he desires a noble task. 2 Now a bishop must be above reproach, the husband of one wife, temperate, sensible, dignified, hospitable, an apt teacher, 3 no drunkard, not violent but gentle, not quarrelsome, and no lover of money. 4 He must manage his own household well, keeping his children submissive and respectful in every way; 5 for if a man does not know how to manage his own household, how can he care for God's church?
Now, this passage is not saying that a bishop must be married. Instead, it is saying that if he is married, he must be married only once. In other words, he can't have multiple wives, or divorce his current wife and marry someone else.
It really would not make sense for Paul to say that all the bishops must be married. For one, Paul himself is a bishop and he was never married! He would be disqualifying himself if he said such a thing. Secondly, if "the husband of one wife" (vs. 2) means that he must be married, then by the same logic, "keeping his children submissive and respectful" (vs. 4) would mean that he must have children. Are non-Catholic Christians really willing to go so far as to exclude from the ministry men who don't have children yet or who had children that are now dead? What about men who only have one child (after all, Paul says "children")? Many people would no longer be able to pastor their churches if these Christians were consistent in their logic.
The main point of the passage is found in the last verse: “if a man does not know how to manage his own household, how can he care for God's church?” All Paul is trying to say is that a bishop must be someone who has all of his affairs in order, who is a good steward of everything in his care. In the first generation of the Church, the priests came from men who already had families. But, over the years, the Church came to discern that men who were called by God to be celibate were better equipped to handle the demands of being a priest and shepherd of God’s flock.
I hope that helps.