'Dark' in the Bible

Because, having the knowledge of God, they did not give glory to God as God, and did not give praise, but their minds were full of foolish things, and their hearts, being without sense, were made dark.

In the belief that you are a guide to the blind, a light to those in the dark,

Let their eyes be made dark so that they may not see, and let their back be bent down at all times.

The night is far gone, and the day is near: so let us put off the works of the dark, arming ourselves with light,