Eph.6:12 For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.
Our battle is not against the lost sinners but against the devil and his angels. Satan in pretense of light actually uses darkness to hide the truth from the lost.
I would like to show 7 kinds of darkness the devil uses to blind men from the light of the gospel.
Darkness of sin
John.3:19 And this is the condemnation, that light is come into the world, and men loved darkness rather than light, because their deeds were evil.
 For every one that doeth evil hateth the light, neither cometh to the light, lest his deeds should be reproved.
Men unwilling to give up their sinful ways and spurning Jesus who died for their sins. Refusing God’s grace preferring their sin over giving their heart to the Lord.
Darkness of ignorance
Eph.4:17 This I say therefore, and testify in the Lord, that ye henceforth walk not as other Gentiles walk, in the vanity of their mind,
 Having the understanding darkened, being alienated from the life of God through the ignorance that is in them, because of the blindness of their heart:
Humanity so busy in the rat race of life kept in darkness. The duty of the Christian is to propagate the gospel, to be a light to those around them. Through personal walk, gospel tracts and outreach ministries of the church. The only way to combat ignorance is through knowledge.
Darkness of religion
2Cor.3:14 But their minds were blinded: for until this day remaineth the same vail untaken away in the reading of the old testament; which vail is done away in Christ.
Perhaps the greatest darkness Satan uses is the darkness of religion. Thinking themselves okay with God by the false religious hopes of vain religion. Religion cannot save the human soul. It is a personal knowledge of Jesus.
Darkness created by carnal Christians
2Cor.4:1 Therefore seeing we have this ministry, as we have received mercy, we faint not;
 But have renounced the hidden things of dishonesty, not walking in craftiness, nor handling the word of God deceitfully; but by manifestation of the truth commending ourselves to every man’s conscience in the sight of God.
 But if our gospel be hid, it is hid to them that are lost:
 In whom the god of this world hath blinded the minds of them which believe not, lest the light of the glorious gospel of Christ, who is the image of God, should shine unto them.
Those of us who are Christians who walk not after the way of faith create a darkness around us by not shining the light of the gospel to those around us.
Darkness of hate
1John.2:11 But he that hateth his brother is in darkness, and walketh in darkness, and knoweth not whither he goeth, because that darkness hath blinded his eyes.
God has shed His love on humanity through the death of His Son. Who died for our sins because of the love of God (Ro. 5:8) How can someone who is supposed to be a Christian claim to hate others? God loved us when we were unlovable. We cannot let the flesh control our lives and we are to love the lost as God does.
Darkness of self-satisfaction
Rev.3:17 Because thou sayest, I am rich, and increased with goods, and have need of nothing; and knowest not that thou art wretched, and miserable, and poor, and blind, and naked:
The world’s baubles can mesmerize a person to the point they think they have no need. We as Christians need to make evident through our testimony that this world is not an end and death is not final. We need to testify there is a judgment after this life and all of the world’s goods will not impact our eternal destiny. The moment we leave this world those things we have accumulated will be forgotten.
Darkness of human wisdom
Rom.1:21 Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened.
 Professing themselves to be wise, they became fools,
There can be a lot said in favor of education but let us say if it takes your mind away from God it is futile. I marvel at the fact that through human “wisdom” man drives a wedge between himself and His Creator.
Col.1:12 Giving thanks unto the Father, which hath made us meet to be partakers of the inheritance of the saints in light:
 Who hath delivered us from the power of darkness, and hath translated us into the kingdom of his dear Son:
 In whom we have redemption through his blood, even the forgiveness of sins:
2Cor.4:6 For God, who commanded the light to shine out of darkness, hath shined in our hearts, to give the light of the knowledge of the glory of God in the face of Jesus Christ.