Start by changing the goal. You are not there to win the argument; you are there to win the person — and you can lose the second while winning the first. Most combativeness comes from forgetting that. Scripture is blunt about the mechanics: “A mild answer breaketh wrath, but a harsh word stirreth up fury” (Proverbs 15:1). A raised voice never made a better case; it just hands the other person a reason to stop listening.

Practically: ask more than you assert. A sincere question — “What do you mean by that?”, “How did you arrive there?” — does more than a speech, because it makes the other person think instead of brace for impact. Concede everything that is actually true — real abuses, bad history, fair points1 — because honesty disarms, and a defender who admits nothing is believed about nothing. And learn what the Church actually teaches before defending it; half of all “combat” is two people swinging at caricatures.

Then aim, as St. Paul put it, to let “your speech be always in grace, seasoned with salt” (Colossians 4:6) — flavorful, not bland, but never caustic. You can hold a position with total conviction and still be gentle about it; in fact the calm person usually looks more convincing, because calm is what we expect from someone unworried about being wrong. The Catholic case is strong enough that you never have to shout it.2