Yes, we can see effects which are proof of things like gravity - we can see that matter attracts in the way that the theory of gravity describes.civ2 said:4. A quite good analogy to God (just an ANALOGY - don't forget this!) would be electricity - humans can't feel it but can see and feel its effects.
(Applys also to gravity and magnetism - we have no organs that can directly sense those - only their results.)
However, we cannot see effects which prove your assertions of a God. We see the Universe - but we don't know that this is an effect of an intelligent being, or something else.
It would be a bit like if I said that gravity was caused by invisible pixies which push things around. I could then say that we see the effects - but the effects are not evidence of invisible pixies, they're only evidence that things attract.