It is quite true that if we took Christ’s advice we should soon be living in a happier world. You need not go as far as Christ. If we did all that Plato or Aristotle or Confucius told us, we should get on a great deal better than we do. And so what? We never have followed the advice of the great teachers. Why are we likely to begin now? Why are we more likely to follow Christ than any of the others? Because He is the best moral teacher? But that makes it even less likely that we shall follow Him. If we cannot take the elementary lessons, is it likely that we are going to take the most advanced one? If Christianity only means one more bit of good advice, then Christianity is of no importance. There has been no lack of good advice for the last four thousand years. A bit more makes no difference.”
—Mere Christianity by C.S. Lewis from Book 4, Chapter 1: Making and Begetting
…but what finally prevents us from saying that the crucified Jesus wasn’t simply a failed revolutionary… What prevents us from taking that route of interpretation is the stubborn and unnerving fact upon which Christian faith is grounded: the resurrection of Jesus from the dead… In the context of first-century Judaism, the clearest indication possible that someone was not the Messiah would be his death at the hands of Israel’s enemies… Yet the first Christians stubbornly and consistently proclaimed Jesus as Messiah… The first disciples went to the ends of the world and to their deaths declaring the messiahship of Jesus. How can we realistically account for this apart from the actual resurrection of Jesus from the dead?
—Catholicism by Fr. Robert Barron pp. 31-32