I do understand irony and see none there.
You mean satire? Parody?
So the Nation, a left-lib. magazine, runs a comic strip in support of same-sex marriage and mocking religious objections to it (really mocking religion in general it seems to me).
You find that to be ironic? Ironic would be that strip showing up on Drudge or the National Review's site. But the nation? Really?