What's the difference between Judas and Peter? goes the popular Bible-study question. "Peter repented' is the refrain. I'd forgotten it was a Matthean setup. And I have to say it gets at the heart of Matthew, in a way.
Like all the evangelists, Matthew's persuading people toward belief. But more than the other ones, Matthew is didactic in its persuasion. You believe in Jesus and in who Jesus is, like Peter, you're in the kingdom, like Peter, despite lapses of faith and serious human weakness.
You don't believe in Jesus and in who Jesus is, you side with the other side, then there's no going back for you, my friend, not if you don't want there to be. The centurions are going to mock Jesus? The joke's on them because everything they say is true. Look for what the wrong ones say, because incomprehension is a didactic theme.
In Matthew, we might learn as much from them as from the disciples. Listen to the crowds, as they chant for Jesus's triumph and soon demand for his crucifixion. If there ever was a direct address to the reader this must certainly be it.
But listen also to the ones who get it right: 'surely this man was the son of God,' or wherever the gospel is preached, this woman will be remembered for her faith'. Follow them, even, to the empty tomb. Don't follow the ones who leave Jesus behind and who must be gathered in again. Follow those who are faithful to Jesus in Matthew, and you follow them into history.
The mission to Jerusalem was a 'failure' not because the message has been changed beyond all recognition, but because the Temple had so corrupted God's people and its system had so embraced hypocrisy that they could not understand it. But the gospel happens anyway. Pay attention! says Matthew. This was all to have been expected.