A random idea I came up with: Accuse homophobes of being Crypto-Islamic fundamentalists wanting to impose Sharia law on the free world.
It's not true, but it's plausible enough for a joke:
Islamic fundamentalist theocracies commonly have anti-homosexual laws on a religious basis, and our "crypto" friends also want anti-homosexual laws on a religious basis.
Islamic theocracies also commonly require women by law to wear highly concealing clothing on the premise that all men are sexual predators with no willpower to resist a revealed ankle. In my experience, homophobes have heavy, heavy overlap with people who issue apologia for man-on-woman rape by claiming the woman was dressing provocatively, thus, in effect, claiming that men should not be expected to have the willpower to control themselves.
I think this meme has shock value since it draws attention to the worst similarities between the allegedly "good" Christian fundamentalists and the obviously evil Islamic fundamentalists.
Of course, I expect that a typical response will be a temporary alliance of convenience with radical Islam to fight the evil of our consistent morality. In such a case, it'd be interesting to see what happens if one of us were to quote the "crypto" in a separate thread where he denounces Islam.