This whole argument has been iterated many times before.
I feel one can only really assume a god exists. It is impossible to know. For one usually defines god as something that cannot be known and something that is outside our perspective, as a whole. The whole spiritual world cannot be known because it cannot be seen, measured or detected. So for arguments sake it's best to leave it out entirely. For we can only ever speculate.
This is my problem in it's entireity. So many things have to be speculated on. An argument made for a god can be applied to any god.