The Christian is to walk by faith and not by sight (2 Cor. 5:7). It is important, then, to know the difference between faith and sight.
Both faith and sight require an organ. For sight it is the eye. For faith it is the capacity to believe.
Each requires a medium. Light is the medium for sight. Faith's medium is the word of God. Faith comes to rational people by rational means. There is no faith without evidence to substantiate it. Romans 10:17 states that "faith comes by hearing, and hearing by the word of God." God's word contains facts, evidence about God and Christ, which lead the rational, honest heart to believe. In stating the purpose for writing his gospel, the apostle John, in reality, gives the purpose for all of God's revelation when he says, "And truly Jesus did many other signs in the presence of His disciples which are not written in this book; but these are written that you may believe that Jesus is the Christ, the Son of God, and that believing you may have life in His name" (John 20:30-31). Jesus, in His prayer on behalf of His disciples, said, "I do not pray for these alone, but also for those who will believe in Me through their word" (John 17:20). Even Satan realizes how faith comes. In His explanation of the "wayside" soil in the parable of the sower, Jesus said, "Those by the wayside are the ones who hear; then the devil comes and takes away the word out of their hearts, lest they should believe and be saved."
Both faith and sight require an object -- something upon which to rest. Sight rests upon those things physical which can be experienced by empirical means. Faith rests upon Jesus Christ. John 3:16 reveals that "God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life." Jesus comforted His disciples by saying, "Let not your heart be troubled; you believe in God, believe also in Me" (John 14:1). When "doubting" Thomas finally recognized the Christ after he had seen the physical evidence of His crucifixion and said, "'My Lord and My God!' Jesus said to him, 'Thomas, because you have seen Me, you have believed. Blessed are those who have not seen and yet have believed'" (John 20:28-29).
There are several reasons for faith's superiority to sight.
Faith has a more extended view than sight. That which is seen is temporary but that which is not seen is eternal. "For our light affliction, which is but for a moment, is working for us a far more exceeding and eternal weight of glory, while we do not look at the things which are seen, but at the things which are not seen. For the things which are seen are temporary, but the things which are not seen are eternal.
Faith is more truthful than sight. Optical illusions abound. One can think he sees something when, in reality, it is something different. Faith is based on the word of God, the truth (John 17: 17). Whatever God's word states is always true.
Faith is more powerful than sight. Read the eleventh chapter of Hebrews, verses 32-40 in particular, and see the great strength of faith. Its strength comes from God's word (Phil. 4:13).