That's a practice, not even a doctrine.
Besides, the verse doesn't say that the bishop must currently be married or have ever been married. It only says that, if he is married, he shouldn't seek to remarry if his wife dies before him. This makes the most sense, as Paul elsewhere writes that widowers shouldn't seek to remarry, so that they may devote themselves wholly to God's work (1 Cor 7:8, 32-34).
Certainly you know the rest of the passage? In particular, the verse right before this one?
But you are not to be called rabbi, for you have one teacher, and you are all brethren.
Jesus must have forgotten that He said this, then? Because just before His Ascension, He told the apostles:
Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you; and lo, I am with you always, to the close of the age.
Scripture doesn't always need to be taken literalistically. If we took this course, the Bible would be full of contradictions just as the atheists claim. Jesus said to call no one rabbi, since we have one teacher, but then He turns around and gives the apostles the duty of teaching? Would you have us believe that Jesus had forgotten? Or perhaps the apostles themselves had forgotten, as they frequently refer to their own disciples as their children, and themselves as their fathers. For example, Paul says in 1 Corinthians 4:15,
For though you have countless guides in Christ, you do not have many fathers. For I became your father in Christ Jesus through the gospel.
Jesus was warning against pride. He employed hyperbole to make His point.
If only you were there in the garden of Gethsemane to warn Jesus about heaping up vain repetitions, as He Himself spoke the same words all three times (Matthew 26:44).
Or, maybe you recognize that not all repititions are vain, and that Jesus wasn't wrong to do what He did. So, you have to prove that the rosary is a vain repetition.
(Side note, I find it curious how it's always the rosary being targeted, never the use of the chotki, and never the Our Father).
You are right to say that there is one mediator between God and men- but who mediates between ourselves and Jesus? (who is also God, mind you)
Firstly, you take this verse out of context. Let me remind you that this is from the same chapter which opens with:
First of all, then, I urge that supplications, prayers, intercessions, and thanksgivings be made for all men
What does it mean to intercede? Wouldn't that be exactly what Bathsheba did for Adonijah (1 Kings 2:19)? In other words, to have someone else bring your petition to someone with the power to grant or deny it? And yet would you say that it's wrong to ask Reverend Tim-Tom to pray for your intentions?
Of course not. Your insistence is that it's wrong for us to ask the saints in heaven- those who have gone before us and have seen God "face to face"- to ask God to grant something we desire. And why is that? It can't be because "the dead can't hear us", because they indeed can. Even the prophet Samuel was called upon by King Saul after he had died, as Saul sought guidance when the Lord had ceased speaking with Him. And Samuel accurately relayed what would happen to Saul the next day (Samuel 28). And then we have the book of Revelation, which makes it sufficiently clear that the saints in heaven are well aware of what is happening on earth- they are the ones presenting our prayers to Jesus. In other words, they are mediating for us. Which brings me to my next point: if we have one mediator between God and man, who is Jesus, who are you to say that there are no mediators between man and Christ?
When you ask your pastor, your husband, your wife, your brother, sister or friend to pray for you, you are doing precisely what Paul urged us to do in the beginning of his epistle, and they are acting as intercessors for us, just as the saints are.