[taion]

And in that sense Tillich isn't that far from, say, Aquinas, who is consistent about asserting that existence is not a "real" predicate and that God's existence is outside of the world and outside of space and time.

You don't even need to squint that hard to see a commonality between Tillich's notion of discussing God symbolically and Aquinas's notion of doing so analogically, not to mention the contrast between finite humans and an infinite God who is beyond understanding. And not to mention that apophaticism – the idea that positive knowledge about God is impossible – has been a feature of Christian theology since the beginning.

So much of this can be taken in ways that not only aren't outside the bounds of Christian orthodoxy, but also align with more sophisticated Christian philosophical understandings of God.

That much, of course, is not why Tillich is controversial!

[jiggawatts]

So… God is mathematics?

[knightoffaith]

Don't know where you got that from.