It is acceptable to be prejudiced against ANY Christian denomination.
And Whites.
And men.
And conservatives.
Bingo. Anytime I've ever heard complaints about religion, it's almost always in the context of "you Christians" and more specifically "right-wing Christian zealots."
I cannot recall the last time I heard someone attack Catholics specifically directly at least outside of FR.
It seems that here on FR however, any counter-discussion or opposing view of Catholicism or the Pope no matter how civil is deemed "an attack."