That assumption has already taken place by the theory of theism (something can't come from nothing, or, as a movement [something, creation] there needs to be a cause of this movement), and you also seem to be assuming that the universe (as in all of existence/space-time) is finite.

First of all, how can something that is utterly independent interact? Complete inherent existence suggests...well...complete inherent existence. It's absurd to suggest something completely independent is connected with other phenomena let alone create other phenomena.

Second, the assumption that our reality is finite is a large one. And dependent upon what? How could there possibly be objective evidence of reality being dependent upon another, seeing as such an existence would be *literally* outside our existence?

Then by this logic, existence would be evidence of non-existence.

This thinking primarily comes from our subjective experience (that is, our limited data and 3-dimensional thinking). Just because there are physical laws in this universe doesn't necessarily they're directed by an invisible hand, or intelligence.

And by this logic, you're assuming that motion is dependent upon outside intelligent direction. This age-old theory of the god of the weather, the god of the sun, etc.,etc. simply falls upon itself. The act of creation (and outside direction) is itself a motion, and therefore according to its own logic would dictate that such a motion demands dependence (or, simply, a cause of a cause; a God of God) and of course that is subject to infinite regression as pointed out earlier. Unless of course you want to say that God exists "just because".