The God of Abraham, Issac and Israel makes moral demands on people. And a lot of people don't like being forced to moral decision. I think that says a great deal about anti-semitism alone.
The real strong suit in Prager's article however, for me, is its argument for Western civilization. If heterosexual marriage contributed so firmly to its anchor, shouldn't what detracts from or undermines that institution be viewed as contributing to the civilization's decline?
As Prager always claims he's for clarity over pursuassion, that's a pretty good shaker-upper.