I've had to do quite a bit of reading recently on the idea of General Revelation and Natural Theology - basically what we can tell about God from looking at the world around us.
I still think Calvin's treatment of it is about as good as they come. He points out that we should be able to tell lots about God from creation, but that we can't see all of it, and we often get bits wrong because we're sinful and blind, and because the blindness and the sinfulness are linked, it's our fault that we don't see God more clearly in the world.
What's interesting though is seeing what the Bible tells us we should be able to tell about God from the world around us.
- That God is real
- That God is powerful beyond our understanding (e.g. Job 38)
- That God is wise beyond our understanding (e.g. Isaiah 55:8-9)
- That God is reliable (e.g. Jeremiah 33:25-26)
- That we should obey God (e.g. Jeremiah 8:7-9, 18:13-15)
- That God is patient
In other words, what we should be able to know about God from the world around us isn't enough that we can be saved. But it is enough that we should be able to see that we desperately need saving, and that we can trust God to do it. It's enough to point us to Jesus, but not enough to replace him.
Being able to see God in the universe doesn't mean that we have authority or power over God - it's because he graciously made us as human beings and made the universe in such a way that we could tell a bit about him from it.
Those things we can tell about God from the universe actually sum up lots of the reasons I enjoyed studying physics so much...
I could put in lots of stuff here about the Barth / Brunner debate, but I can't be bothered, and I don't think it would help that much.