When you show them that verse about the conception of Jesus they just stare at you and don't know what to say, after that it's up in the air what they might say.
I personally don't spend time debating with those who want to believe in three gods, I let them believe whatever they want. To me its apparent that they either do not study or they don't have the Spirit of Truth the Holy Ghost.

Now there are those who see it but don't understand it completely because it is the greatest mystery. I like to instruct those people and help them to come into the light of understanding. I think we waste too much time with those whose names were not written in the Lambs Book of Life before the foundation of the world.