Noah Millman remarks near the end of his discussion of Christianity and human rights:

A Christian doctrine that says, in an Eisenhower-esque vein, “in the long term, you can’t believe in democracy and human rights unless you believe in religion, and I don’t care what it is” winds up, effectively, endorsing at least some other religions as at least “sort of true.” Which I think any orthodox Christian would find highly problematic.

Some orthodox Christians might react that way, but I’m not sure that Orthodox Christians would, and I am confident that Catholics (especially post-Vatican II Catholics) would not. It is Catholic teaching that other monotheistic religions are “sort of true” on account of their monotheism, and other religions are true to whatever degree their teachings reflect Truth (that is, Christ):

The Catholic Church rejects nothing that is true and holy in these religions. She regards with sincere reverence those ways of conduct and of life, those precepts and teachings which, though differing in many aspects from the ones she holds and sets forth, nonetheless often reflect a ray of that Truth which enlightens all men.

It is almost impossible for other religions not to be “sort of true” when judged this way. Of course, as a matter of religious teaching being “sort of true” isn’t enough for orthodox Christianity, and there’s no way that it could be, but for the purposes of this discussion I don’t think Ross would have any difficulty accepting that other religions are “sort of true.” For that matter, heresies are “sort of true,” but what matters to the orthodox Christian is how they depart from the fullness of the truth found in orthodoxy. I assume this is why Ross chooses to describe beliefs in terms of heresy rather than using a different word. Orthodox Christians have been declaring certain doctrines to be “sort of true” for two millennia. It is because of their partial truth that these doctrines have been rejected as misleading and spiritually dangerous.

Let’s come back to Ross’ argument. He writes:

This brings us back to the core of my argument: Namely, that much of contemporary secular liberalism depends on assertions that are potent and widely persuasive only because most Westerners are still deeply influenced by Christian premises about the nature and destiny of man.

It’s the last part of the sentence that doesn’t make sense to me. As an empirical matter, it seems that most Westerners are not “still deeply influenced by Christian premises about the nature and destiny of man.” I don’t disagree with Ross when he describes secular liberalism as “a system of thought that looks rather like a Christian heresy,” but as Ross knows heresies don’t always share the orthodox premises about God or man, and there are always some orthodox premises that a heresy necessarily rejects. If ancient heresies often centered on questions of Christology and theology, modern heresies usually represent departures from orthodox premises concerning “the nature and destiny of man.” If that’s right, the popular appeal of modern heresies depends on orthodox Christian premises’ losing their influence in much of the West. Democracy and human rights seem to serve as a sort of substitute religious worldview in the post-Christian parts of the West because there is no longer any confidence that God created man in His image and likeness and then became man that we might become gods.

P.S. All the different citations and re-uses of Tertullian’s phrase in contemporary debates are amusing, not least because Tertullian’s Christianity was rigorist, uncompromising with the secular culture around him, and later became heretical.