Dark matter is just another particle with unfortunate name. Like antimatter having just an opposite charge but still being matter. Or the Higg's not being particles which make up God despite the silly name.
The darkness of dark matter simply describes how we can't as yet measure and quantify it. Once we do though it'll just be matter like every other. So using m-theory to make it into something especially unusal is reading too much into it or something.
In other words, things are either real or not. If real, they're composed of particles however exotic. If not real they don't exist anyway. If God is real, it's made up of particles and thus bound to the laws of physics like everything else.