How confident are you that your beliefs are true? How confident are you that you have not been deceived? Most people believe that what they believe is true, else they would not believe it. When we recognize that we have been deceived, then we change our beliefs (hopefully for the better). Everyone uses their reason at times; some people just happen to use reason more than others.
St. Robert Bellarmine said in his little catechism,
"This is why, although a man might conclude that faith seems like something contrary to reason, human reason is weak and for that reason it is easily deceived..."
Did you notice that? "human reason is weak". He did not say that it is powerless, or that it is perfect. He said it is weak. Thus, we are called to realize that reason can only do so much for us. It cannot answer all of our questions. I know this is contrary to much of modern society (especially those who worship science as the answer to all our questions), yet if human reason is weak, and (as Bellarmine said) it can be deceived, then we have to accept the fact that we may reason wrongly.
Faith might seem contrary to reason, but that is only when reason is failing. In reality, faith in God and His revelation is perfectly reasonable. After all, God created reason, and so all He does is in accord with reason, even if we do not understand how that is so. For example: I do not understand why God chooses to allow infants to die, yet I know that He is good and only does that which is perfect. That shows that my reason is weak, but that faith steps in to fill the gaps of my reason.
Do you allow faith to do its part in your life? Or do you insist on reasoning through things? When we believe that our reason can answer any question, then we have fallen into pride and forgotten our own weaknesses. This is why Scripture says that faith is a "gift of God", because it is not natural to us, and without it we cannot properly understand truth. So use reason, but recognize its limitations, and do not resist the work of faith in your heart. It is the only way to know God rightly.