"Satan" here is referring to the demons who follow Satan as well as to Satan himself. Alternate translation: "If Satan and members of his kingdom are fighting among themselves" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Jesus uses a question to teach the people. This can be translated as a statement. Alternate translation: "If Satan ... his kingdom will not last." or "If Satan ... his kingdom will fall apart." (See: [[rc://en/ta/man/translate/figs-rquestion]])
"For you say that it is by the power of Beelzebul that I make demons leave people." The next part of his argument can be stated explicitly: Alternate translation: "For you say that it is by the power of Beelzebul that I make demons leave people. That would mean that Satan is divided against himself" (See: [[rc://en/ta/man/translate/figs-explicit]])
"If I ... by whose power do your followers force demons to leave people?" Jesus uses a question to teach the people. The meaning of Jesus' question can be made explicit. Alternate translation: "If I ... then we must agree that your followers also drive out demons by Beelzebul's power. But you do not believe that it is true." (See: [[rc://en/ta/man/translate/figs-rquestion]] and [[rc://en/ta/man/translate/figs-explicit]])