To see light two things are absolutely necessary: firstly, a light source bright enough to see, and second a mechanism in your body namely eyes and brain to perceive the light.
What is true physically is also true spiritually.
We are all born spiritually blind and in darkness. Satan has blinded us through the fall of Adam so we cannot perceive spiritual truth, we do not acknowledge our sin and we cannot recognise the glory of Christ, all our thoughts are earthly (II Cor.4:4, Matthew 15:14, John 9:39). We stumble around in the dark trying every way to find direction in life and satisfaction and always looking in the wrong places.
The only way to be made seeing is by regeneration by the Spirit of God (John 3:3, II Cor.4:6). The light source is Christ and the gospel and our spiritual eyes need to be opened. Hence the NECESSITY of the prayers of Christians for their nearest and dearest, their friends and colleagues that GOD WOULD WORK, if it be his will, to illuminate their hearts. Check the prayer of Elisha in II Kings 6:17. Simultaneously we need to be given ears to hear the effectual call of the gospel. Did dead Lazarus have the ability to hear Christ’s words to come out of his tomb? Of course not! Once life was given back to him, he could! Dead eyes don’t see and dead ears are deaf!