We Don't "believe",it's just that it doesn't require the suspension of disbelief to adhere to the theory of Evolution,and it is backed up by a wealth of evidence,which is why it can reasonably be considered fact.
The theory of Evolution is the product of painstaking observation and experiment.Firm conclusions are only drawn, when rigorous examination consistently supports the hypothesis.
On the other hand,Creationism begins with it's conclusion:God exists,made everything in a week less than 7,000 years ago,has unlimited power,and - indications to the contrary notwithstanding - Loves you an awful lot.
