Spiritual darkness is sin, falsehood, and separation from God, who is light with no darkness in Him at all (I John 1:5). Anyone who claims fellowship with God yet walks in darkness lies, and anyone who claims to know Him yet does not keep His commandments is a liar. Hatred of a brother in the church is darkness, because love of the brethren is walking in the light, and there is no middle ground between love and hate. Satan, once the light-bearer Lucifer, became the adversary and father of lies, and he rules the realm of darkness. People do not leave that darkness on their own; God opens their eyes, they recognize and confess their sins, and they are forgiven and set apart by faith (Acts 26:18). Darkness hides sin, as the looting during the 1977 New York blackout showed, and Satan disguises it with lights, as in Las Vegas or at Christmas, because he transforms himself into an angel of light. The sins behind such glitter eventually come into the light of day, and they can never be hidden from God. Believers must make sure the light in them is not darkness (Luke 11), seeing evil clearly and avoiding it. The contrast of light and darkness runs from Genesis 1 to Revelation 22. In the end, those who overcome and keep God's commandments walk in the light of the New Jerusalem, where there is no night, while liars, the sexually immoral, murderers, and idolaters remain outside in the dark.

This world loves darkness, where many believe they can hide their actions—lying, cheating, stealing, and more—thinking no one will see or find out. Jesus confirms in John 3:20 that those who practice evil hate the light and avoid it, fearing their deeds will be exposed. Yet, the light of God surpasses even the sun, revealing all secrets, for nothing is hidden from Him as stated in Hebrews 4:13. The light of truth exposes the sinful deeds of men, illuminating what is concealed in darkness. We have been given God's truth to light up our lives, ensuring we do not dwell in darkness. Jesus declares Himself the true light of the world in John 12:46, promising that those who believe and follow Him will not remain in the dark. As He teaches in John 3:21, those who live by the truth come to the light, so their deeds may be seen as done in God. Therefore, we must walk in the fullness of His light, practicing what pleases Him, allowing our little light to shine brightly in this increasingly darkening world.

Spiritual darkness is the biblical opposite of light: error, ignorance, sin, evil, and the works of Satan, just as light stands for truth, goodness, and God's redemptive work. Those who worship light itself, rather than its Creator, fall into spiritual ignorance. Darkness comes from rejecting God's law, which leaves people unable to tell light from darkness (Isaiah 5:20). The Devil, who has no truth in him, is the father of those who live in lies, so deceit becomes their native language, and the god of this age blinds the minds of unbelievers lest the light of the gospel shine on them. Judas shows its depth: after Satan entered him, he left Christ's presence and went out into night, doing the work of darkness in the hour of the power of darkness. Darkness is also death; the plague of darkness fell on Egypt. Those who do evil love the night and fear exposure by light. Sin separates people from God and so from spiritual understanding. Even those who hold only the form of knowledge, as hypocritical Jews and cultural Christians do, remain in darkness. Satan also uses false light, such as the Enlightenment, to lead people into deeper darkness. God delivers His people from the power of darkness and calls them into His marvelous light, so they must walk as children of light and expose the unfruitful works of darkness. In the Millennium God will shine truth into every mind, and in the New Jerusalem all traces of darkness will be gone.

Spiritual darkness is the universal symbol and condition of sin, error, ignorance, and death, the opposite of light, which stands for truth, goodness, and God's redemptive work. It belongs to Satan, the Prince of Darkness, who blinds the minds of unbelievers so that the light of the gospel cannot shine on them, and who focuses a false light on the pleasures of sin to draw people deeper into darkness. Those who worship created light rather than the Creator are in spiritual ignorance. Darkness shows itself in calling evil good and good evil, and in a world of lies and deceit where truth has become a foreign language. Judas left the light of Christ's presence under Satan's control, and John's words "and it was night" mark the hour of the power of darkness. Having only a form of knowledge, as the Jews had in the law, is also darkness, because it produces mere appearance without the true light that comes from the heart. Sin separates people from God and so from spiritual understanding. Darkness is not only a condition but a fear, since sinners shrink from the light and God must call them to it. Christians were once darkness but have been called out of it into God's marvelous light and are to walk as children of light. God is light and in Him is no darkness at all; at the end the light of God will obliterate every trace of darkness, with no spiritual night remaining.