You honestly can't figure out what he's saying here? He's saying an ethic prohibiting abortion is not a distinctive "belief" of a Church based on faith in a supernatural source of revelation. If it were that, "Don't abort your children" would have the same status as, say, "Go to Mass on Sunday." It's something you could not credibly propose to somebody outside of your faith. You could not propose it to civil society.
But the prohibition on abortion is based on the verifiable human status of the victim of the act. An atheist can see that. Nat Hentoff can see that.
It has its religious aspects, to be sure. It has its philosophical aspects as well. But it is solidly rooted in Natural Law. Thus it can be required of one's fellow citizens in a State which still Constitutionally prohibits any "religious test."
Any other questions, Alex?
I think *Thou shalt not murder* would cover it.
So, yes, there IS a religious prohibition.
Perhaps Pope Francis has too much faith in the mental acuity of his listeners.