I think it depends. It depends on what kind of faith one have. There is nothing wrong in having a reasonable faith. There is nothing wrong to believe that you will be dropped safely in Roxas if you take a Toril-Roxas jeep or a taxi. Me believing that North Korea exist even though I have not been there is still reasonable. I may not have been to North Korea but it is already universally known that North Korea exist or there are countries around North Korea that would tell us that NK exist. There are instances that believing in something without evidence is not that irrational. Like believing that my 'ka-text' is a human and not a dog or that I am really texting my friend and not some one else. These beliefs are not irrational because they are directly supported by evidences[scientific] and logic.
However having blind faith is a different thing. Believing that you can catch a bullet or that you are bullet proof is stupidity. Believing that you will enter the gate of heaven when you die in a suicide bombing will not only kill yourself but also kill other innocent people is also stupid and irrational. This is blind faith. Having a very strong belief in some thing with no evidence [or implicit faith/fideism] is irrational. That kind of faith is bad and that it could cause complications in one's life.
All I can say is that one should base its beliefs on scientific inquiry and reason. Not just on mere faith alone. If you have faith then make it sure that it is supported by scientific evidence and logic.