The originators of this movement, John Milbank, Catherine Pickstock, and Graham Ward, are Anglicans and they teach at Cambridge University. Postmodernism disintegrated modernity's Enlightenment certainties. The logic of secularism is imploding. Their pronouncements were as much without foundation as everyone else's. Radical Orthodoxy points out that what remains is words.
People talk to one another.
Logos is the only certainty. This means that all other disciplines are part of, and inevitably rooted in theology. All philosophy is inside theology, and it can't get out. The result is that we can no longer say that the virgin birth, the resurrection, miracles, etc. Radical Orthodoxy rejects the idea that there are fixed secular standards.