Why did Matthew and Mark remove Satan?
Today the answer is clear! Luke told Theophilus that Jesus died on a Roman cross in a crucifixion carried out by Roman solders at the decision of the Roman Governor. Luke also makes clear that the “chief priests and rulers delivered him to be condemned to death and crucified him.” Luke sometimes indicates that Pilate and Herod had a prominent role and sometimes presents the 'Men of Israel' having a great responsibility. In any event Luke has spread the blame. Peter tells the Sanhedrin that they acted in ignorance. On the cross, Jesus prayed for the forgiveness of his enemies as did Stephen. More significantly Luke state that Jesus was “delivered up according to the definite plan and foreknowledge of God” and that Men united against him, “to do whatever thy hand and plan had predestined to take place.” According to Luke, those involved in the crucifixion were agents of God. Thus Acts can also be considered irenical in the same sense as Luke. Furthermore Acts is not polemical; it is critical of the high priests but Luke does not personally attack Theophilus. Thus reconciliation and forgiveness is an important theme presented by Luke as part of his irenical presentation to Theophilus.
Mantel has shown that Jesus was not guilty under Jewish law of any offense. Perhaps the early church in their polemics questioned the validity of the Sanhedrin proceedings and the Matthew and Mark modifications were made to support those allegations. Matthew and Mark, by including a night time hearing, attempt to show that a 'kangaroo' hearing was conducted by the High Priest in violation of the Rule of Mishnah that all trials had to be conducted during day light hours. Luke's account of the trial of Jesus when compared with Matthew and Mark is favorable. Matthew and Mark are clearly anti-Judaic representing later traditions and post-schism rewriting. This can not be said of Luke-Acts. Luke is not anti-Semitic. Luke, who is clearly knowledgeable about what Ezekiel taught, having alluded to him many times, was aware that there was no concept of collective responsibility. Matthew and Mark have created such a concept.
More importantly, Matthew and Mark removed Satan from the picture. In Luke, Satan enters Judas and then Judas meets with the chief priest and agreed to betray Jesus. Satan is the chief instigator in Luke but has no role in Matthew and Mark. Since Matthew and Mark are creating Jewish collective responsibility, there is no place for Satan in their rewriting.