So polite!

I’m a member of the Church of Jesus Christ of Latter-Day Saints, and I really appreciate you looking into what we prefer to be called! Depending on who I’m with and how casual I feel like being, I might call myself Mormon if they already know that I believe in Christ and am Christian. To a stranger, I would give the full title, unless they used Mormon first. Than I would make a casual note about it being a nickname, make sure they know our true name, and not worry about it after that.