A good scientist (I think) is one who approaches every question from three angles: (a) What does the question look like if I'm right?, (b) What does the question look like if I'm wrong?, (c) What does the question look like if I make no assumptions whatsoever about the outcome? The latter is actually really hard to do (and probably can never be done truly on anything).
I would say that someone approaching the world with "I am a rational being, created by a rational god to live in a rational universe with the ability to learn about it" probably isn't a wholly bad way to approach science. It would certainly be better than "I will look for any answer, except one I don't like", which I see from a lot of atheists as well as a lot of Christians. But, having said that, a scientist needs to be "agnostic" about his work - general rule: never trust anyone's research if they're doing it with a point to prove (a lot of "funded by" research tends this way).
Also, I would say that to be a good believer, you should question your faith. IMHO, faith that hasn't been tested isn't really faith. It scares me the number of people (in all sorts of realms, and from all sorts of beliefs) who don't question their core beliefs. Though, I can understand it to a degree - big, "meaning of the universe" questions can be scary (as is "what if I'm wrong?"), but one should still ask them, and frequently. It's a good antidote to becoming a freaky religious weirdo (atheists can be this, too - and actually, so can agnostics even, though it's a lot rarer). :-)