Substance dualism, which I cannot imagine a Christian could not believe, states that there are two fundamental substances: the material and the spiritual. The material being the world we observe, one thing causing another causing another, the spiritual being the soul or whatever you'd like to call it that consciousness is made of. A traditional philosophical question that comes out of this is how exactly they interact, if they're fundamentally different substances then spirit interacting with ordinary matter would require violating the conservation of energy. If they're the same substance then you don't have to worry about violating conservation of energy, but spirit becomes material and the soul is demystified.