...among competing hypotheses, the one with the fewest assumptions should be selected. Other, more complicated solutions may ultimately prove correct, but—in the absence of certainty—the fewer assumptions that are made, the better.
Creationism fails because it HAS to assume the existence of some sentient, potent, willful force (for example god)
Sentient, potent, willful forces are everywhere; you're one; I'm one. We have a great deal of first-hand experience with them. We know, to a great degree, how they work and why they work. God is pictured as similar, but moreso and without our flaws. This may be an assumption, but it is not a great leap; my kids think I'm a lot like them only moreso and with fewer flaws (if only they knew!); why shouldn't we think that our Father in Heaven is so? But read on...
whereas non-theistic science only needs to rely on empirically demonstrable data.
Non-theistic science needs all sorts of very unscientific things to get anywhere at all. Curiosities, hunches, inklings, flashes of insight, desires, ambitions, envies, jealousies, and such like; not to mention Reason (with a capital "R" meaning the unprovable assumption that reasoning itself is valid), plus all sorts of sensory input and many other things that scientists use, every day, without having the foggiest idea where they come from and how they actually work. Further, non-theistic science assumes that order can arise from chaos without plan or purpose, which has never been demonstrated (perpetual motion machines, anyone?). Postulating a better designer than the designers we know first-hand is one kind of "assumption"; postulating something utterly foreign to everything we think and do (like the spontaneous emergence of order from chaos) is an assumption of an entirely different, and more significant, nature.
If theists such as yourself could provide empirical evidence for the existence of this world making superbeing it would be quite a different story. But so far such evidence is lacking.
The evidence is all around us, and within us. His works bear witness to his power and intelligence; and our own reasoning ability, our moral sense, our aesthetic sense, even our sense of humor, etc, bears witness to some of His other attributes. What? Are we to really to think that such things can arise, unbidden, from inert matter?
Every time we act, we change the natural course of events in the universe; we don't violate the physical laws, but rather provide them with fresh input; input they wouldn't have had had we not chosen to act. That's a tiny little taste of God's creative power -- a gift, from Him, and a witness to who He is. Want to see me rule over the natural laws that you apparently want to make your master? Look no further: by a shear act of will I have caused this post to take shape in the universe -- something that never would have happened had the universe been left to it's own devices. Goodness, people! You're immortal creations of the Divine! Why are you so intent on seeing yourselves as nothing but accidental hiccups in a universe doomed to maximum entropy?