Contrary to popular opinion there is a spiritual war going on right now. Those who mock that suggestion, thinking that spiritual reality is a myth reserved for the primitive mind, do so at their own peril. There is a devil, and he has schemes intended to defeat humans and deface God:
Finally, be strong in the Lord and in the strength of his might. Put on the whole armor of God, that you may be able to stand against the schemes of the devil. Ephesians 6:10 (RSV)
To be willfully ignorant of such schemes is to cede victory to the devil. To know the schemes and ignore them is foolish and will produce the same result.
The designation of the evil one is "Satan." The word means "accuser." He accuses without the foundation of truth. In the original garden, he accused God to Adam and Eve of not being forthright with them, thus not being fully good. After Adam and Eve sinned, he began his shame campaign on the human race. His hatred is always aimed at God, and he tries to deceive those whom God loves. He loves to reinterpret circumstances to show that God is not both sovereign and good. Those who accept that perspective are held captive by such deception.
His main scheme with believers is to distract by accusation. It works like this: The believer trusts God for full forgiveness and cleansing. With a purified soul the believer can attack the strongholds of deception and evil, and Satan loses. So, Satan focuses on getting the believer to doubt his cleansing and remember his failures. Now, the believer can't see the opportunities to displace darkness with light, because he is focused on self.
An example of this was evident in the first presidential debate. Donald Trump' supporters groaned when he needlessly spent several minutes defending himself against accusations instead of focusing on the message he needed to deliver. There's a lesson here: you can't focus on yourself (either in defending or in promoting) and still see the opportunities to attack your enemy.
Many a Christ-following father has grieved the waywardness of a son who refuses to honor his parents and legitimate authorities. The son justifies his actions and accuses his father of being a hypocrite. If the father takes the bait, he disqualifies himself from the battle. He might needlessly try to defend himself or slip into condemnation based on the accusation. The truth is that he is still the father and the forgiven believer who has the name of Jesus and the discernment of the Spirit. Based on truth, he can engage in prayer and in communicating truth in love.
As long as we are susceptible to accusation we will easily be taken out of the fight. Defending our own righteousness is foolish. We have no such righteousness to defend. But followers of Christ have been given the righteousness of Jesus, which needs no defense. When Satan suggests that we are not fully clean and qualified to represent the kingdom of God on earth, he is accusing God of an incomplete salvation. We don't have to take the bait. The salvation given through Jesus satisfies God and that is enough.
The times are crucial. There is no time for foolish fighting. The real war is raging. The people of the ultimate victor must engage in it or our generation will walk in deeper darkness.