He's a Catholic in name only.
An apostate.
A Catholic is anyone who declares himself to be a Catholic.
I don’t know about this guy. I have known homosexuals who do not practice it, are basically what you’d call “abstinent”. They would not qualify as “apostates”. If Sullivan is arguing a political position of civil law, I’m still not sure he’d be apostate. If he’s arguing that the Church be required to perform their weddings and recognize their “marriages”, then he probably would be apostate.