What happens when you shine a flashlight in the face of a person who is totally blind?

Nothing. A person who is blind cannot see the light. If a person cannot see the light how can he comprehend it much less apprehend it; his eyes are not capable to take in the light so as to be able to see what is in front. He lives in darkness. This is also true spiritually of the unregenerate man, the person who has not had his eyes of understanding opened up to see truth, the truth of the Light of the gospel. In 2 Corinthians 4:3-4 that the reason a doesn’t see the light of the truth of Gospel of Jesus Christ is because their eyes are blinded to the truth; and in 1 Corinthians 2:14 we are told that the natural man is incapable of understanding the truth because of his sin nature. Jesus said that unless a man is born again by the Spirit, he cannot see the kingdom of God (John 3:5). This is the cure to spiritual blindness. Let us therefore pray that the Lord will open the eyes of the spiritually blind and even for ourselves that we might suffer from spiritual blindness. Lord, open our eyes that we might see the beauty of your light in your word of truth; let your word be a lamp to our feet and light to my path (Psalm 119:105); for you, O Lord, are the light that lights my lamp enlightening my darkness, according to your word (Psalm 18:28).