"Having the understanding darkened, being alienated from the life of God through the ignorance that is in them, because of the blindness of their heart" (Ephesians 4:18).
It is a tragedy for a person to have blinded eyes, but infinitely worse to have a blinded heart. No one ever willfully chooses to be sightless, but spiritual blindness is a product of the human will.
After Christ had given sight to the man born blind, the Pharisees still refused to believe, so Jesus said to them: "For judgment I am come into this world, that they which see not might see; and that they which see might be made blind. . . . If ye were blind, ye should have no sin: but now ye say, We see; therefore your sin remaineth" (John 9:39,41).
Like these ancient intellectuals, it often seems that modern intellectuals are incurably blind. They profess to teach science and philosophy of the highest complexity, but their understanding is darkened and their hearts are blinded when it comes to the saving gospel of Jesus Christ. As Paul says: "If our gospel be hid, it is hid to them that are lost: In whom the god of this world hath blinded the minds of them which believe not, lest the light of the glorious gospel of Christ, who is the image of God, should shine unto them" (II Corinthians 4:3-4).
Even very religious people, people who believe in God as Creator, may blind themselves when confronted with the truth that the Creator must also become their Savior. "But their minds were blinded: . . . even unto this day, when Moses is read, the vail is upon their heart" (II Corinthians 3:14-15).
Nevertheless, Christ came as "the light," and when anyone will simply in faith "turn to the Lord, the vail shall be taken away" (II Corinthians 3:16), and the gospel will "shine unto them" (II Corinthians 4:4). HMM