Why must God and evolution be separate
It doesn't have to. But distinction is very important to minds that are self identified as intelligent. To share ideas with colleagues or to teach ideas to students, the distinctions become crucially important. Without the distinctions, those in an endeavor of ongoing research either lose patience for what is being discussed and/or feel communication is in domain of absurd / pointless. People rely on understandings that conform to earlier or recent teachings.
why couldn't evolution be a creation of God used as tool a God machine to create life, and as a way to continue the life without God having to directly effect every creature's exact actions?
Again, there is not a great reason why this couldn't be the case, but also nothing compelling for the masses why the God concept (especially traditional concept) needs to be involved in sharing ideas about biological evolution.
Creationism deals with question and preconceived answer of 'how did all this (including me) get here?' From there, purpose of life and in managing affairs of a society follow. Hence what religion is essentially up to.
Physical sciences (unlike behavioral sciences) are ambivalent toward that question, and see it as very unnecessary given the preconceived notions about the data available for research. Mainly the notion that we need not know / understand anything about a metaphysical past to determine what the physical phenomenon is 'showing' us. IOW, we will derive our own metadata from the (false) idea that the evidence itself is providing.
Besides we all believe in at least some type of science, i doubt anyone here believes God resides in us and works our every bodily function.
I know God resides in us, and I believe it. In my understanding, it is knowledge that God resides in us, and is how we know what we know.
Like many around me, I have misplaced faith in notion that there is world outside of me, and that it is showing me something very important. Something that impacts my very physical life, and that I have evidence showing me my physical life is in doubt, that survival is a struggle and physical death inevitable.
Knowledge tells me consistently, often that I am manifesting world perceived as outside of me, and that I have given all meaning to these things (phenomenon). The world is showing me precisely what I desire to 'hear' while I pretend otherwise and play a very elaborate game of ignorance, whereby I, and others, can conclude (via faith) that this world is not of my making. I have no knowledge of what will come next.
I am becoming accustomed to the fact that we are evidence (we are the proof) of Intelligent Design. Our consciousness demands meaning, and our sciences requires it. In some ways, to not see this is at best absurd. It is akin to maintaining an infant awareness of our role in 'scheme of things.'
Most of what I've said so far doesn't need a "God" concept to explain it, to understand it. The God outside of Me concept is dying. I say good riddance.
Evolution as theory needs an intelligent agent to explain it, to rationally understand the design. Evolution outside of consciousness is meaningless. It is rather obvious that what is going on 'here' intended for itself to learn about itself. To deny this is folly.