"Freethinkers are occasionally thoughtful, though never free..."

Freethinkers are occasionally thoughtful, though never free. In the modern world of the West, at any rate, they seem always to be tied to the treadmill of a materialist and monist cosmos. The universal sceptic, in Asia or in Antiquity, has probably been a bolder thinker, though very probably a more unhappy man. But what we have to deal with as scepticism is not scepticism; but a fixed faith in monism. The freethinker is not free to question monism. He is forbidden, for instance, in the only intelligible modern sense, to believe in a miracle. He is forbidden, in exactly the same sense in which he would say that we are forbidden to believe in a heresy. Both are forbidden by first principles and not by force. The Rationalist Press Association will not actually kidnap, gag or strangle Sir Arthur Keith if he admits the evidence for a cure at Lourdes. Neither will the Cardinal Archbishop of Westminster have me hanged, drawn and quartered if I announce that I am an agnostic tomorrow. But of both cases it is true to say that a man cannot root up his first principles without a terrible rending and revolutionising of his very self. As a matter of fact, we are the freer of the two; as there is scarcely any evidence, natural or preternatural, that cannot be accepted as fitting into our system somewhere; whereas the materialist cannot fit the most minute miracle into his system anywhere. But let us leave that on one side as a separate question; and agree, if only for the sake of argument, that both the Catholic and the materialist are limited only by their fundamental conviction about the cosmic system; in both thought is in that sense forbidden and in that sense free. Consequently, when I see in some newspaper symposium, like that on Spiritualism, a leading materialist like Mr. John M. Robertson discussing the evidence for spiritualism, I feel exactly as I imagine him to feel when he hears a bishop in a mitre or a Jesuit in a cassock discussing the evidence for materialism. I know that Mr. Robertson cannot accept the evidence without becoming somebody quite different from Mr. Robertson; which also is within the power of the grace of God. But I know quite well he is not a freethinker; except in the sense in which I am a freethinker. He has long ago come to a conclusion which controls all his other conclusions. He is not driven by scientific evidence to accept Materialism. He is forbidden by Materialism to accept scientific evidence.

The Thing: Why I am a Catholic (1929)