your sexual orientation is not a choice - correct.
whereas being a homophobe is a choice - not sure about this one, it may be a choice or not, but being decent and polite to gay people is a choice and something we should do ... even refusing to bake a gay wedding cake can be done decently and politely.
I'll add one of my own ...
A gay couple getting married is a choice, i.e. same-sex marriage is a choice.
The problem happens when gay activists expect everybody to agree with them about gay marriage, and then throw a hissy fit when they find out other people sometimes hold different opinions or have different beliefs.
As far as I know, the christian baker doesn't actively seek out gay couples and harass them, he doesn't gatecrash gay weddings, etc.
The gay couple sought him out.
Did they know beforehand that he had bible-based beliefs, and sought him out to put him on the spot?