I disagree with the idea that Satan can't put thoughts directly into someone's head. What about:
John 13:2 "And supper being ended, the devil having already put it into the heart of Judas Iscariot, Simon's son, to betray Him,"
John 13:26-27 "Jesus answered, "It is he to whom I shall give a piece of bread when I have dipped it." And having dipped the bread, He gave it to Judas Iscariot, the son of Simon. Now after the piece of bread, Satan entered him. Then Jesus said to him, "What you do, do quickly."
In John 13:2, "put it into the heart" is literally rendered "thrown it into the heart" bringing up the imagery Paul used. "Above all, taking the shield of faith with which you will be able to quench all the fiery darts of the wicked one" (Ephesians 6:16). What John was alluding to what the fact that Judas had already decided to betray Jesus having approached the chief priests earlier that day (Luke 22:3-4).
But all this does is support the concept that Satan is the source of temptation. "Let no one say when he is tempted, "I am tempted by God"; for God cannot be tempted by evil, nor does He Himself tempt anyone. But each one is tempted when he is drawn away by his own desires and enticed" (James 1:13-14). Satan is responsible because he encouraged Judas to sin. Nothing in this passage suggests that the encouragement came in the form of planting the idea directly into Judas' head. The fact that Satan manipulated Judas and encouraged him to think about betraying Jesus is sufficient. Understanding this also causes us to realize that Judas bore responsibility for choice that he made. He wasn't forced to think of nothing else or had his free-will removed from him.
The fact that "Satan entered him" (John 13:27; Luke 22:3) means that Judas let Satan reign over his choices. He gave himself over to following Satan instead of following Christ. It is the opposite of what Christians do, who "put on the Lord Jesus Christ, and make no provision for the flesh, to fulfill its lusts" (Romans 13:14). Once again, the fact that "Satan entered Judas" doesn't absolve Judas' responsibility for what he did. Judas realized that. "Then Judas, His betrayer, seeing that He had been condemned, was remorseful and brought back the thirty pieces of silver to the chief priests and elders, saying, "I have sinned by betraying innocent blood"" (Matthew 27:3-4).
Jesus placed the source of sin as the things we think about (Mark 7:20-23). Thus Peter tells us to make preparations to control our thoughts and our actions. "Therefore gird up the loins of your mind, be sober, and rest your hope fully upon the grace that is to be brought to you at the revelation of Jesus Christ; as obedient children, not conforming yourselves to the former lusts, as in your ignorance; but as He who called you is holy, you also be holy in all your conduct,because it is written, "Be holy, for I am holy"" (I Peter 1:13-16). Paul urged, "And do not be conformed to this world, but be transformed by the renewing of your mind, that you may prove what is that good and acceptable and perfect will of God" (Romans 12:2). These ideas would be out of our reach if Satan could, at any time, force us to think sinful thoughts.