As influential as Jesus' teachings were, they wouldn't hold nearly as much power unless there was something else accompanying it; something that proved His authority. I make such a claim because we see the same reasoning in the book of Acts. In Acts 5, the Jewish Sanhedrin was wondering what to do with this new sect of Jesus followers who won't obey their cease and desist orders. Gamaliel, a respected teacher, comes before them and says,
The Sanhedrin should've understood this. In John 2:19, when Jesus drove out the moneychangers, they asked Him what kind of authority he had to dictate what should and shouldn't happen in God's temple. Jesus replied "Destroy this temple and I will raise it up on the third day" speaking of His resurrection.
Some like to point to Jesus as being a great teacher as the explanation for His popularity. But reducing Jesus to merely a good teacher neither explains the magnitude of His influence nor does justice to the things He actually said. Of course the teachings of Jesus were revolutionary and profound. But Jesus was unique. He claimed to speak with the authority of God, and backed up that claim by going to the cross, dying, and rising again. It is because of the resurrection that Jesus is held to be the source of authority on matters of God and mankind and it is because of the resurrection that we celebrate this season.