There is a similarity between eyesight and faith simply in the effect that they have—one on the physical, the other on the spiritual. Nevertheless, in terms of II Corinthians 5:7, faith and eyesight are opposites. Recall that Hebrews 11:1 says that "faith is . . . the evidence of things not seen." Faith is the conviction of what we have heard but cannot see. "Faith comes by hearing" (Romans 10:17).
Man says. "Seeing is believing." So when a man sees something, he is convicted, and his mind, then, is inclined to what he has seen. In the life of the righteous, faith is the controlling factor that motivates his conduct. The importance of eyesight is true in the physical realm, but it means almost nothing in the spiritual realm.
Consider physical Israel. The Israelites saw multiple miracles in Egypt and in the wilderness, but they seem to have profited them almost nothing. They saw the Nile turn to blood. They saw the frogs. They saw the lice. They saw the darkness. They saw the hail. They saw the fire on the ground. They saw the murrain kill the cattle. They saw the firstborn die. They saw the Red Sea part. They saw the pillar of fire and the cloud. They saw water coming out of the rock. They saw manna on the ground every day for forty years. They saw all those things.
Yet, what they saw did not affect their minds spiritually at all because eyesight means almost nothing in terms of the spiritual. Faith is the foundation, the assurance, the substance, the confidence, of things not seen—the invisible realm of God. In terms of faith, what a person can see with his eyes is more likely to frighten him and create doubt than it is to build faith.
Faith, according to Ephesians 2:8, is a gift of God. It is a gift because we did not have real spiritual faith until God began to call us. It is a gift because, by a mighty miracle, God opened our minds to enable us to understand His Word so that we can process the evidence we hear from His Word and make right choices relevant to His Kingdom.