It's not a belief system at all. It's a knowledge system based upon demonstrable proofs that can be replicated by anyone (and everyone) else, and, as such, have predictive qualities set in a mathematical model. No one in science is expected to take anything on 'faith'. If you walk into a college physics course and say "Hey, I don't think that gravitation exists" the teacher would say, 'Great, prove it.'
And those two little words - prove it - are the chasm that separates science and reason from faith and belief. And it's one hell of an abyss between them.
You ask a religious person for some 'proof' and what they give you back is 'you must have faith.' For the world's largest GOD based religions (and not all religions are GOD based), they have between them not a single shred of evidence, not a single iota of proof about Jesus being God, about the Jewish God existing, or the existence of Allah. Zip. Zero. Zilch. Nada. People believe them based on faith - or as others see it, based on imagination, hallucination, and wishful thinking. The best you can get out of the three of them combined is 'look at the world/universe, it has to be true', which is no proof at all.
A religious person would say that you have to have faith in order to get god/religion to work for you. A scientist will tell you that you can doubt gravitation all you want but if you jump off the Golden Gate Bridge you're still going to fall, and the speed at which you hit the water is going to be determined by 9.81 m/s (32.2 ft/s or 22 mph) for each second of your descent up to the terminal velocity. No believe required. Splat.
And, sho 'nuff, each and every person who has jumped off that bridge - 1,200+ - have fallen down. Not a single one fell up. Not a single one hovered. And though we have lots of evidence from interviews with those that have survived it that you have a long time to really regret the decision on the way down, no amount of faith, belief or prayer has ever stopped the fall.
Science and reason/rational thought do not DENY the existence of god, because you can't prove a negative. Lacking proof, they instead say, 'perhaps'. Maybe yes, maybe no. They say: Hypotheses non fingo, as Newton did. They also say, in the immortal words of Carl Sagan:
Extraordinary claims require extraordinary evidence.