Being therefore always of good courage, and knowing that, whilst we are at home in the body, we are absent from the Lord (for we walk by faith, not by sight); we are of good courage, I say, and are willing rather to be absent from the body, and to be at home with the Lord (2 Cor. 5:6-8).
From the connection in which we find here the phrase, “by faith,” we learn that faith serves the same purpose in the spiritual world that sight does in the natural world. Faith is our spiritual eyesight. Things which are eternal, we see not (2 Cor. 4:18). Our hope waits for things not seen (Rom. 8:24-25). Hope is based on faith (Heb. 11:1). Our faith, looking through the telescope of divine promise, reveals to us our eternal home.
But eyes cannot see without light. Sight is the product of light. Without spiritual light, the eyes of our understanding would never be enlightened (Eph. 1:18). We would never believe. God’s word is light and belief, or faith, is the product of divine testimony. Belief comes of hearing and hearing by the word of Christ (Rom. 10:17).
It necessarily follows that to walk by faith is to walk as the word of God directs, because faith could not exist without testimony. To do anything by faith is to do it because God requires it as He directs. An act of faith is imply an act of obedience. We cannot do what is not authorized by faith.
“By faith, Noah, being warned of God concerning things not seen as yet, moved with fear, prepared an ark to the saving of his house” (Heb. 11:7). He believed a flood would come. The warning caused his belief. But he prepared the ark by faith.
If the position I take is correct, we will find that he had instructions to build the ark. Turn to Genesis 6:13-22 and you will find the word producing faith. “And God said unto Noah (v. 13) make an ark of gopher wood,” etc. (vv. 14-16).
Detailed instructions were given for building the ark—dimensions, etc. Paul says he built by faith. But Moses says, “Thus did Noah; according to all that God commanded him, so did he” (Gen. 6:22). Here we have the definition of the phrase “by faith” as used by Paul. “By faith is the same thing as “according to all that God commanded him, so did he.” If God had not authorized the building of the ark, Noah could not have built it by faith, and his building it would not have pleased God or saved Noah.
“Without faith it is impossible to please him” (Heb. 11:6). Therefore, unauthorized service does not please God.