I’d just like to say one thing here, if I may.
It may seem very clean and sharp in your mind, but these screenplays that a few posters have written here do not play out in an actual conversation. Besides for this, whether you win or lose you lose- if you spend time talking to a missionary that’s a loss.
My advice is avoid these conversations like the plague. You have nothing to gain but more than nothing to lose by it. Use your creative minds not to develop dialogue but to develop excuses or even LIES (if needed) to get you out of the situation, such as by saying, “I’m so sorry but I can’t stop now because my house is on fire”, and run away.