The devil is a liar. Jesus said, "When he lies, he speaks his native language, for he is a liar and the father of lies." Jesus also said, "He was a murderer from the beginning, not holding to the truth for there is no truth in him." (John 8:44)
How do we counteract the devil's lies? Know the TRUTH. Study God's Word. Know the Scripture and yes, memorize the Word. When the devil tempted Jesus in the wilderness, He answered him with Scripture. We can do the same, but we have to know the Word.
We must know the Truth to repudiate the devil's lies. If we don't know God's Word, how will we recognize his lies?
When we saturate our minds and thoughts with God's Word, we will recognize the devil's lies. "Then you will know the truth and the truth will set you free." (John 8:32)