According to Scripture, Satan does the following things to keep those who have not believed in Christ in spiritual darkness.

1. Deny His Existence

One of the favorite ways in which Satan operates is to get people to deny that he exists. He seems to be most effective when people do not believe there is such a creature as the Devil. If he can get people to doubt his existence, then he can do much of his work without their knowing.

Disguise

We find from the Bible that Satan has often approached people in disguise. For example, in the Garden of Eden he came in the form of a serpent to Adam and Eve (Genesis 3). Paul warned the Corinthians that he appears as an angel of light (2 Corinthians 11:14).

To His Advantage

This unbelief in his existence works to Satan's advantage. When people are either uniformed or misinformed about the existence of the Devil, they become like the Sadducees in Jesus' day, who did not believe in angels or spirits. When someone rejects the idea of Satan's existence they are an easy target for him to manipulate.

2. Blinds People To God's Truth

The truth of the gospel is what sets people free. Satan attempts to blind people from that truth.

And even if our gospel is veiled, it is veiled to those who are perishing. In their case the god of this age has blinded the minds of the unbelievers, to keep them from seeing the light of the gospel of the glory of Christ, who is the image of God (2 Corinthians 4:3,4).

3. Energizes His Own Ministers

Satan gives power to his own ministers.

It is no great thing therefore if his ministers also fashion themselves as ministers of righteousness, whose end shall be according to their works (2 Corinthians 11:15).

4. Controls People's Hearts And Minds

Satan has the ability to control hearts and minds.

And Satan entered into Judas who was called Iscariot, being of the number of the twelve (Luke 22:3).

5. Hinders The Gospel

The message of the gospel is hindered by the Devil.

When anyone hears the word of the kingdom and does not understand it, the evil one comes and snatches away what is sown in the heart; this is what was sown on the path (Matthew 13:19).

6. Prevents People From Hearing The Gospel

Satan's main goal is to prevent people from hearing the good news about Jesus. The message of forgiveness offered through Jesus Christ sets people free. Jesus said.

So if the Son makes you free, you will be free indeed (John 8:36).

7. Misrepresents The Truth

Satan lies, denies, and misrepresents the truth. To Eve he said.

And the serpent said unto the woman, You shall not surely die (Genesis 3:4).

8. Takes Away Gospel

He also takes away that which the unbeliever has heard.

And those by the way side are they that have heard; then comes the Devil, and takes away the word from their heart, that they may not believe and be saved (Luke 8:46).

Satan attempts to get the unbeliever to think about subjects other than the gospel of Christ.

9. Encourages False Trust In Religion

Finally, Satan attempts to get people to falsely place their trust in themselves, religion, or good works. He wants people to feel religiously satisfied, but without having a saving knowledge of Christ. The Bible says.

There is a way which seems right unto a person, but the end thereof are the ways of death (Proverbs 16:25).

10. Goal Is Destruction

His ultimate goal is the destruction of people.

And be not afraid of them that kill the body, but are not able to kill the soul: but rather fear him who is able to destroy both soul and body in hell (Matthew 10:28).

11. Hope For Escape

Fortunately, there is hope for unbelievers to escape the traps of the Devil.

And a servant of the Lord must not quarrel but be gentle to all, able to teach, patient, in humility correcting those who are in opposition, if God perhaps will grant them repentance, so that they may know the truth, and that they may come to their senses and escape the snare of the Devil, having been taken captive by him to do his will (2 Timothy 2:24-26).

Summary

Satan has his methods with unbelievers. He wants to keep them from hearing the good news about Christ - the forgiveness of sins. To accomplish this he prevents people from hearing, blinds them to the good news, takes away the good news once they have heard it, and has them falsely trust in something apart from Christ and His gospel. This is his strategy to keep people from hearing and believing the truth about Christ.