'Dark' in the Bible

Whose thoughts are dark, to whom the life of God is strange because they are without knowledge, and their hearts have been made hard;

For you at one time were dark, but now are light in the Lord: let your behaviour be that of children of light

And have no company with the works of the dark, which give no fruit, but make their true quality clear;

For our fight is not against flesh and blood, but against authorities and powers, against the world-rulers of this dark night, against the spirits of evil in the heavens.