No, in regard to the gay characters, it would be getting rid of lame crap that the story never needed in the first place.
EDIT - And what one dimensional Christian characters do you have in mind? Off hand I can't remember any.
The religious elements are much more central to Preacher than are any individual freakish characters. I'm just guessing, but the religious elements are sure to offend many fundamentalists and some Catholics. The problem is that modifying the religious stuff enough to quiet theologically conservative Chriistians would eviiscerate Preacher. Modifying or eliminating most (or all?) of the gay characters wouldn't.
Now if you picked a story where unattractive gay characters were central to the story, for instance the play and movie The Boys in the Band, you couldn't toss them out because they're completely necessary, no matter what anyone of any political persuasion thought. I'm sure there are modern works of popular culture which include peripheral, gratuitous elements that insult subgroups of people of faith, but that's only a little true of Preacher.