'Darkness' in the Bible

‘The sun shall be turned into darknessAnd the moon into blood,Before the great and glorious day of the Lord comes.

Now, watch! The hand of the Lord is on you, and you will be blind, [so blind that you will be] unable to see the sun for a time.” Immediately a mist and darkness fell upon him, and he groped around, seeking people to lead him by the hand.

to open their [spiritual] eyes so that they may turn from darkness to light and from the power of Satan to God, that they may receive forgiveness and release from their sins and an inheritance among those who have been sanctified (set apart, made holy) by faith in Me.’