it hasn't effected me to the same degree as would bigotry directed at me if I was black and gay
DING DING DING.
Since you so desperately need me to clarify this: Bigotry is bad, ok?
~BUT~
Comparing two different forms of prejudice, each with very different real-world consequences, is invalid. Being opposed to the largest and most powerful religion in Western countries is absolutely nothing like being opposed to the identities of oppressed and/or minority groups. This is because of power structures and institutionalised prejudice but more importantly because of religion, race, and sexual orientation being different things.
Look, you can believe antitheism is wrong all you want - all I'm saying is that it is not the same as homophobia or racism. Just like racism is not the same as homophobia, and neither are the same as sexism, and sexism is unlike transphobia, and transphobia is not comparable with speciesism. Different prejudices need different discussions. Don't drag one group's struggle into an argument over another.
Insisting people stay on topic in a discussion, and not appropriate the experiences of unrelated groups in an attempt to silence their opposition, is not immature. On the other hand, appropriating the experiences of unrelated groups instead of actually bothering to make any argument supporting your own stance is a mark of immaturity.