Faith implies that you don't have a perfect knowledge of something. While so many in the world today insist on fully understanding every point of doctrine before they will accept it, the Lord's way is different. Jesus Christ told Peter: "Blessed art thou Simon Bar-Jonas, for flesh and blood hath not revealed this unto thee, but my Father which is in heaven."
God Himself will tell us what is true and how to act. We do not need to fully understand the reasons why. If we already understood everything God knows, we wouldn't be exercising faith. We'd be acting on pure knowledge.