Physicist Neil Turok:
I think that if science is to overcome the disconnection with society, it needs to be better able to explain science’s greatest lesson: that for the purpose of advancing our knowledge, it is extremely important to doubt constantly and to live with uncertainty. Richard Feynman [the theoretical physicist] put it this way: “This attitude of mind—this attitude of uncertainty—is vital to the scientist, and it is this attitude of mind which the student must first acquire. It becomes a habit of thought. Once acquired, we cannot retreat from it anymore.”
Prometheus Unbound 
This could be said in our discussion on atheism and creativity as well. The state of uncertainty, even fear, is the most creative. The fundamentalist and the skeptic both shut the door by saying this book is the truth or this set of rules and principals are unrefutable.
Although I don’t think it becomes a habit of thought. It’s more like exercise, something that must be actively maintained. Certainty is a natural comfort zone.