For those trudging through the 1000 word posts on Matthew 24, here is a much simpler and shorter essay.
My brother claims that Jesus told his disciples he would return “immediately after” the fall of Jerusalem in AD70. Jesus did not return at the appointed time, and hence the authority of his words are discredited.
What this position commits my brother to is an early dating of the book of Matthew, namely that it is pre-AD70. From Daniel Wallace’s introduction to Matthew: “I fail to see any motive for preserving, let alone inventing, prophecies long after the dust had settled in Judaea, unless it be to present Jesus as prognosticator of uncanny accuracy (in which case the evangelists have defeated the exercise by including palpably unfulfilled predictions).”*
This is a dilemma. If Matthew has an early dating, then even if Jesus is wrong about his own return, he is correct in his prediction of the destruction of the temple. Again, I think the most natural reading is that Jesus doesn’t claim to return in AD70, but of course this means that a later dating is possible and hence Jesus’s claim about the temple isn’t necessarily predictive. I’m tempted to think (along with Wallace) that this amounts to a conclusive argument for an early dating of Matthew.