John 1:9 – That was the true Light, which lighteth every man that cometh into the world.
2 Cor 4:4 – 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.
2 Cor 4:6 – For God, who commanded the light to shine out of darkness, hath shined in our hearts, to give the light of the knowledge of the glory of God in the face of Jesus Christ.
Romans 1:16a – For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth…
Romans 10:9 – That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved.
Why were the Dark Ages called that? Because there was no Scripture or gospel that went forth during that period! Light and darkness- believers have the light of the gospel in them and they can testify to that.
From these verses we see that believers have a spiritual understanding, or ‘light’. They know what the gospel is and can articulate it. Then belief or faith secures that light. This is a difference one should exhibit.
The lost, contrariwise, are in spiritual ‘darkness’. They have no understanding, let alone belief of faith. They are not able to articulate it and often use extra-biblical phrases such as, “I asked Jesus into my heart‘, or ‘I’ve decided to follow Jesus‘. Notice these both lack a specific mention of the gospel, what it is, and that they have faith in it and believe it. Anything lacking of the clear gospel of Jesus Christ is no gospel at all – Romans 1:16, Galatians 1:8, John 5:24.
2 Cor 2:14 – But the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him: neither can he know them, because they are spiritually discerned.
This verse explains that the lost person (‘natural man’) has no ‘light’ or spiritual understanding, hence they can’t understand Scripture, let alone the gospel.
I recall that the day I read, understood, and believed the gospel by faith something in me changed; I was different. Later, I understood spiritually that it was the ‘light’ of the gospel that God gave me by grace. Praise God.