Jesus said, when the comforter or the Paraclete will come in John’s Gospel, he will guide us to all truths and he will remind you of my teachings. So that implies that Jesus’s teachings will become corrupt at some point in time. And this paraclete or Comforter will come. He will remind people of Jesus words and he will prophesy.
So Muslims believe that to be the prophet Muhammad (Pbuh) because after Jesus Christ, Islam is the last world major religion with over 1 billion followers.