If there's one thing I could get every single well-meaning Christian to understand, it's that "real Christians are X" is an explicitly religious argument that depends on religious truth claims. And when you ask non-Christiana to accept that, you're demanding that they accept your religious claim.

The long European history of Christians slaughtering each other over the debate about who is or isn't a real Christian has failed to educate them, so I'm not super optimistic.