I disagree.
The core of any belief system is like that. Remember what I mentioned once before? "One can only utilize the essence of baye's theorum: What's the probability of this, if that is true?". A system of logical conclusions regarding knowledge are founded on a system of knowledge gained by faith (presumption). Such is the boundary of logic, it requires something upon which to build. Would you propose that an "intelligent designer" is an irrefutable assumption? That "I am", is an irrefutable assumption because if you are not, the statement itself is moot. If "you aren't" then there is no you to know there is no you and thus the connudrum is resolved painlessly. There is no down side to such a presumption. Assuming however "god is", is not so neatly resolved. That "god is" cannot be shown. That "I am", is demonstrated in the act of the assertion. That "god is"... can only be justified with emotion. Logically, that's quite perilous IMO - depending of course on your intended outcome. If understanding nature is your intended outcome, the presumption of god is as bad as you can do I'd think. If feeling that you understand nature is the intended outcome, then the presumption of god is a pretty decent bet.
The more serious repurcussions of the presumption, the more perilous the assertion.