If something is an unchangeable fact about someone, then one should not be prejudiced against them on that account. If gay means same sex attracted, then I think there are cases of persons who are gay, and they can't change that. Christianity may require that they be celibate, but there is no just prejudice against them based on who they are attracted to. I realize "phobia" is probably an inapt term.
A group of Christian gays might apply to march in a Gay Pride parade with the intent to carry a sign that says "Proud to be Gay, Celibate for Jesus." Now the parade organizers would probably deny the application, but that would be religious prejudice. But if I am right in thinking that these people can't, as it were, "pray the gay away," then to treat them poorly because they are same sex attracted would be anti-homosexual prejudice.