I'm surprised that you say this. I would have to say that I find that the opposite is often true. I think that Catholic Freepers are sometimes condescending and/or hostile to non-Catholics.
Can you point out some specific instances of an anti-Catholic bias?
Three posters come immediately to mind. I won't name them, because then courtesy dictates I should ping them, and I do not wish them here based on what so many other threads have become.