Will We Ever Have Any Idea How Widespread Medieval Atheism Was?

I've long wondered whether atheism has not become much more widespread in Christendom since the 17th century, as it sometimes seems, but whether what has changed has been first and foremost the acceptability of publicly expressing doubts about God's existence, doubts which were there all along. Sometimes people don't see something, not because it's hidden, but because it's been there in plain sight for so long that they no longer think about it. The fact that "early" atheism, from the 17th century on into the 18th, seems not to have developed so much as to have suddenly appeared, fully formed, without a long process of individual people wrestling with the issue, being torn between faith and atheism and going back and forth between the two, and atheist positions gradually developing theough this process, suggests that atheism was there all along and waited only for permission to record its existence in published writing. Who knows how much it had previously circulated in private letters and conversation.

But just recently some other things have struck me, things not at all hidden, facing me the whole time in plain sight, just waiting for me to notice: medieval proofs of God. For instance, the Quinque viæ or Five Ways of Thomas Aquinas in his magnum opus Summa Theologiae.

The argument of the unmoved mover, the argument of the first cause, the argument from contingency, the argument from degree, and the teleological argument: Aquinas' five proofs of God, as beloved today as ever among many theologians and as tedious as ever to the rest of us.

In Aquinas' day Latin was the primary written language from Iceland, to Lithuania, to Hungary, to the non-Muslim half of of Spain, and everywhere in that Latin-writing region Catholicism was firmly in control, and from Aquinas' time no piece of Latin writing has survived containing anything even remotely resembling something which could even be misconstrued as an atheistic sentiment. Among the Catholics were a few Jews, as monotheistic as they were. And on the borders of this Latin world were territories controlled by Greek Orthodox Christians and Muslims who were all every bit as monotheistic as the Catholics and Jews. And Aquinas wasn't writing for an audience in China or southern Africa.

So who was Aquinas arguing with?

Can it be that he and the many other Medieval theologians who constructed proofs of the existence of God were arguing above all with themselves, because subconsciously even they knew how ridiculous religion was?