Don't worry, God helps those who are in His army. Our Lord told His disciples that the Holy Spirit would be speaking through them. While we're not holy Apostles and most of us aren't very holy at all, we are not left without help when we have to stand up for the faith.
Even if we talk only about human means, debating skills and audacity can be learnt and practiced. A method of talking with students that Jan talks about above is a good example of how a willing heart can reach up to people and unite in the search for truth that the academic life is about.
President Kaczyński of Poland, who died last Saturday, and who was a law professor, said, "all my experience says that good work, honest performance of duties, just treatment of people, unites people of different worldviews."
While theology is obviously not about consensus but about truth, *the *truth, little worth is our search for the truth if we look out for number one in the discussion and ignore the others for our own advancement as we force our positions (the often, maybe too often used quotation from Aquinas comes to mind: "in my love for the truth let me not forget the truth about love").
By contrast, if we approach people with an example of good, honest work and equitable treatment, we can acquire them for our cause or at least create a setting in which we can talk to them like a man talks to a man, without a verbal or intellectual equivalent of bloodshed. Where we fail to make a point intellectually, academically, our lives and our bonds with people will still be there. The same way, with President Kaczyński, whom I quoted a while above, now people remember first of all that he was a good man. They remember that he was warm and kind and that he and his wife gave a beautiful example of marriage. This is not a lecture given in a university hall.
You will have plenty of opportunity to practice debating and public speaking by the time you become a professor, but your lack of love of confrontation may be not a liability but a blessing if you use it well.