Salvation Is of the Lord

Creation itself gives light to Man as the image of God; Lights every man that comes into the world: John 1:9. This is the light of reason, the ability to make sense of things, but this is not sufficient, for man is blinded by sin.
There is the Light of conscience: Proverbs 20:27 with Romans 2:14ff This also is not sufficient, being corrupted by sin.

There is the Light of Scripture: Romans 2:17ff the knowledge of revelation: this also is not enough; to know, but not do is defective, but this is necessary, for how shall they believe if they do not hear.
Matthew 6:22ff double minded. Halting between two opinions is deadly.