This is a mark of pride, not an insult, though it's best used when referring to oneself.
Contrary to some people's beliefs, neither gays nor atheists have an agenda to rule the world; most gaytheists are understanding and intelligent.
Person 2: "Because I'm gay."
Person 1: "I'm a gaytheist. I don't believe homosexuality exists."
Person 2: "You're wrong. I'm gay."
Person 1: Are you?