Well, here is my explanation that completely dumbfounded this atheist:
Look at the verse again.
and came and lived in a city called Nazareth. This was to fulfill what was spoken through the prophets: "He shall be called a Nazarene."
Matt 2:23
This verse says it was "spoken", it was not "written" down. This is why there is no verse in the Old Testament. The Old Testament has the prophesies that were written down, but this one was oral.
The Old Testament Jews took great stock in oral tradition. Jesus condemned them for holding to human tradition at times when it went againt the Word of God. The Talmud is a collection of some of oral sayings that were said by Moses but were not written down in the Pentateuch.
Obvious, one of the prophets orally taught that the Messiah would be a Nazarene, not meaning He would be from the Nazarite order, but that He would be raised in Nazareth. This was not written down. This was never written down, but it was carried on from generation to generation by word of mouth.
So what Matthew wrote was correct. It was spoken by the prophets. He did not write that it was ever written down. That was a false assumtpion from my atheist opponent, and many readers on this thread.
But why do Protestant commentators go through all sorts of contortions to come up with explanations that any skeptic would just laugh at? Why avoid the simple, direct explanation in favor of complicated explanations that seem to be mere cop-outs?
The reason is that the simple, direct explanation is too Catholic! In order to accept the simple explanation, one must admit that oral tradition can sometimes contain the words of God. It means that, although Jesus condemned tradition when it goes against the Word of God, that sometimes oral tradition can contain the Word of God.
And since oral tradition can sometimes contain the Word of God, Matthew can quote from oral tradition and show how Jesus fulfilled it.
But for Protestants to admit that oral tradition can at times be valid would set a dangerous precedent. They would prefer to have contorted explanations that makes makes them laughingstocks to outsiders than to admit that their Catholic brothers could be right.