It's pretty clear cut. David created the xenomorph. Xenomorph isn't the deacon. The deacon existed before, and the engineers knew of it, even worshipped it. Xenomorph has human characteristics that David fused into the pathogen. I imagine the next step is fusing machine qualities into the xenomorph. I'm assuming Awakening was supposed to be David completing the bio-mechanical beast and attempting to fuse himself into it so as to become the devil himself.