Kant on arguments from God

I. Kant on the Ontological Argument
Kant begins with the ontological argument. This argument was originally developed by St. Anselm, rejected by St. Thomas Aquinas, but adapted by Descartes.
He maintains that while the idea of God contains the idea of a necessary being, this idea does not tell me whether or not God exists. If a know that a triangle has three angles, I still don’t know whether there are any triangles.
Existence is not a property. If I think of a white cat sitting on my desk, and I think of an existing white cat sitting on my desk, I am thinking of the same thing.
Existence is not a predicate
Existence is not a predicate, that is, a property. (Obviously in grammar, the word “exists” is the predicate of the sentence “God exists,” but this is not what Kant has in mind.) If I think of a white cat sitting on my desk, and I think of an existing white cat sitting on my desk, I am thinking of the same thing.

II. The Cosmological Argument
As Kant understands the cosmological argument, it rests on the premise ‘Every event has a cause.” But this applies only to the world of experience as it appears to us, and can’t be applied to something we can’t experience.
Further it rests on the idea of a necessary being, and therefore only works if the ontological argument works, which it doesn’t.
This is a bit puzzling
Kant’s second response to the cosmological argument strikes me as a bit puzzling. If we can’t prove the existence of a necessary being by the ontological argument, does it follow that we can’t prove it some other way? If Kant had criticized the ontological argument in a way that showed that the idea of a necessary being made no sense (that would be Hume’s critique) then the statement would make sense.
What I think he is getting at is that even if you show that a necessary being exists, that being needn’t be the traditional God unless the ontological argument works. Though Aquinas’ fourth way is somewhat different from the OA, but it would reach the same conclusion if it were to be accepted.

III. Kant on the design argument
Considers it “the oldest and clearest and most accordant with the common reason of mankind of all the arguments for God.”
But it would only prove an architect of the world, not a necessary being or a perfect being. You need the ontological and cosmological arguments for that.
So the arguments for God fail
But so do the arguments against the existence of God. Theoretical reason just doesn’t work in this area. That’s not the fault of God, it’s a question of using the wrong tool.
Kant said he needed to deny knowledge to make room for faith. However, we need to take a close look at what philosophers (or theologians for that matter) mean when they use the word faith.

So do we commit metaphysics to the Humean flames?
No. We are burdened by questions that we as reasoners can’t ignore, but which we don’t know how to answer either.
The ideas help us regulate our thought. It is useful to act as if we knew there was a God, a self, and a cosmos.
Does he mean that these ideas are useful fictions, or does he mean that they are ideas we must presuppose as rational beings? Kant scholars are divided on this.