This one god could be of the deistic or pantheistic sort. Deism might be superior in explaining why God has seemingly left us to our own devices and pantheism could be the more logical option as it fits well with the ontological argument's 'maximally-great entity' and doesn't rely on unproven concepts about 'nothing' (as in 'creation out of nothing'). A mixture of the two, pandeism, could be the most likely God-concept of all.
