“If, therefore, the light that is in thee, be darkness, how great is that darkness.” (Mathew 6:23) 
Well if I just write it like this, “If, therefore, the darkness that is in thee, be light, how great is that light.” Life of man normally is a mixture of light and darkness. Still the life of a number of persons is totally dark; but the life of a few persons is all light. Jesus warns man against darkness (Luke 11: 35). Man considers his light as the real light of life, but his supposed light is actually all darkness, and if all his supposed light is not light but only darkness, then all his life is full of total darkness.
The question is what then darkness is? The evil works of man are darkness. According to Eph. 5: 6-7, 11 Darkness denotes the sins, evil and unfruitful works of darkness. The darkness of sin is sheathing the life of man and lurking inside his life creating a great threat to The Light of his life. Due to sin man has lost his holiness of soul and spirit. It is a spiritual blindness getting possession of the spiritual eyes of man’s soul. Rev. 3: 17-18 Therefore the presumed light of man is darkness which is deceiving his life. 
There is no contact between Light and Darkness. Worship of all abomination of desolation is darkness and sin. (Mathew 24: 15). All the gentile gods & goddesses, all idols and devilish religions and their signs are abomination of desolation which are the cause of darkness in the life of men (Isa. 44: 19, 2- king 23: 13). “Ye cannot drink the cup of The Lord, and the cup of devils: ye cannot be partakers of The Lord’s table, and of the table of devils.” (1-Corinth. 10: 21). If you are a partaker of devils your life suffers from total darkness and no light is left in your life. “------for what fellowship hath righteousness with unrighteousness? And what communion hath Light with darkness? And what Concord hath Christ with Belial? Or what part hath he that believeth with an infidel? And what agreement hath The Temple of God with idols?” (2-Corinth. 6: 14-16). The Temple Of God must be full of light and not Darkness. And you are the temple of God. The darkness turns your temple into the temple of devil. (Ezek. 8: 6, 12). 
“Take heed, therefore that the light which is in there be not darkness. If thy whole body therefore be full of light, having no part dark, the whole shall be full of Light,” (Luke 11: 35-36). Therefore to gain The Light of Life you must do as it has been prophesied to do :- “And if thou draw out thy soul to the hungry, and satisfy the afflicted soul; then shall thy light rise in obscurity, and thy darkness be as the noonday.” (Isa. 58: 10). He must believe the words of Jesus, “-----I am the light of the world; he that followeth me shall not walk in darkness, but shall have the light of life.” (John 8:12). “-----Light is come into the world, and men loved darkness rather than light, because their deeds were evil. ------But he that doeth truth cometh to the light.” (John 3:19-21). Only the light of Jesus has the power to vanish away your darkness. If you have some darkness with your light, come to Jesus Christ. He shall cast away your darkness and shall turn your whole life in “A Temple of Light.”
Best wishes and blessings from:-  Rev. Dr. Jashobeam Singh                               Administrator Christ Vision Network