Satan is very clever at lying. In fact, one of his names is 'The Father Of Lies". He lied to Adam and Eve in the Garden, and he is still lying today. Whether you can see this or not, he is trying to lie to you and me.
What are some of his lies to us? For some, he would try to persuade us that we have sinned too greatly for God to forgive us. Or, he might tell us that our sin is not that big of a deal. He probably has told us that we are basically good, and reminded us of some of the good deeds we have done. One thing I have noticed that the devil does is to tell a person things that are not true about another person. We can see this happen a lot in marriages. Both spouses end up with distorted versions of what the other person is thinking. Satan loves to stir up strife between people.
Some other lies are that God doesn't really love us, or that when bad things happen to us, God is punishing us. He makes it complicated for us to bring our sin and guilt to the Cross. Why? Because of the event of the Crucifixion, Satan is now defeated. He is disarmed. But he is still around speaking lies. His end has not come yet, but his end will come with the victory of the saints (redeemed human beings) one day, and he will be here no more to bother us. But God has allowed him to stay on earth for a season. God has also given us some weapons so we can fight against him and those in the kingdom of Darkness.
In Ephesians chapter 6, God tells us that the type of warfare we are involved in is spiritual, not physical. We are to be in prayer. We are to know God's word of truth. We are to live out the Gospel in our lives. The light of the Gospel dispels the darkness. We are to become discerning people so we can tell the difference between the truth and the lies. We need to digest the word of God, spiritually speaking, and be worshipers of the True and Living God.
In Isaiah 58, God tells us that we can set the prisoner free (prisoners here are people who are enslaved by sin). If we can have a good understanding of who God truly is, and we could see what kind of work the Enemy of our souls is up to, we could be victorious in battle. There will be struggles and difficulties, but the chains can be broken because 'Greater is He who is in you, than he who is in the world.'
Satan uses half-truths as well, such as 'God is all-loving' and God is all-forgiving'. While the Bible says that 'God is love', God is still going to punish sin and sinners in hell for eternity. God's love is so great and deep that it caused Him to provide the ultimate sacrifice for our sins, so we won't have to go to hell for eternity, but we can have our sins forgiven, only if we repent and turn to God, and trust Jesus as our Savior from sin.
So, I encourage you to be in God's Word continually, not in a legalistic way, but to feed upon it, grow in it, and be able to tell the difference between the Truth and the lies.