Read the words........
Jhn 1:3 Through him all things were made; without him nothing was made that has been made.
Gen 1:27 So God created man in his [own] image, in the image of God created male and female created he them.
Jhn 1:4 In him was life, and that life was the light of men. Every living person was given the light.
Jhn 1:5 The light shines in the darkness, but the darkness has not understood [fn] it.
Luk 11:35 See to it, then, that the light within you is not darkness.
Just because the light of the Spirit is not seen, does not mean that it is not there. It is just not understood.
What do you think being born again means. All truth comes from within, not without. This is where the light of truth has forever been.
Jhn 1:4 In him was life, and that life was the light of men. Every living person was given the light
What is not to understand?
I think you need to check out Romans. Specifically: Romans 3:1-28 for starters. NOWHERE does it say that God’s Holy Spirit indwells unbelievers. He does not. He indwells the believer ONLY. I think you are getting the concept of man’s being made in the image of God confused with some kind of idea of natural holiness that man possesses. As the above verses (among many many others in Scripture) point out, mankind is naturally wicked. He is NOT “holy” in any sense of the word. Hence, mankind’s need for a Savior who is. Any “good” mankind thinks he’s doing apart from Christ is “as filthy rags” (Isaiah 64:6). Christ’s promise of His Spirit is to the believer only (See Luke 24 for the account of Christ’s resurrection and this promise.)
By the way, the fact that mankind was given the truth only means he’s accountable for not believing on Christ for the forgiveness of sins. As for the idea that mankind has some type of inner cleanliness — Christ debunks that in Matthew 15:18-20:
But those things which proceed out of the mouth come from the heart, and they defile a man. For out of the heart proceed evil thoughts, murders, adulteries, fornications, thefts, false witness, blasphemies. These are the things which defile a man, but to eat with unwashed hands does not defile a man.” From the inner core of mankind he is sinful from birth. There is no “inner goodness”, “inner truth”, or “inner light”. There is only darkness apart from Christ.
Also see Jeremiah 17:9 - “For the heart is deceitful above all things and desperately wicked. Who can conceive it?” Certainly no indicator of any inner goodness or light!