But your claim was of a theory that Matthew originally ended at 28:8 - I can't seen anything in the link in support of this - perhaps it isn't in the available chapter.
True -the chapters available in the preview don't give the full picture. Just to say it is available as an e-book, which is cheaper than the hardback. There are other chapters detailing the specific material Riley thinks was edited in. This includes the story of the guards, and the reference to the mission to all nations in the last few verses of ch.28, which, he says, gives significance to the record of the meeting in Galilee, and therefore must have been an addition because previous references to the mission to the Gentiles and the end of the age (such as in 24:3) also appear to have been additions.
But on that - his argument seems to be that Mark borrowed not from Matthew, but from some lost proto-Matthew. To which the easy repost is - well if there is a proto-Matthew, surely there will also be a proto-Mark. It seems again like cherry picking.
He thinks Mark's copy of Matthew did contain most of the additions, such as the Sermon on the Mount, which Mark omitted.
The first chapter talks about some 17 so-called 'doublets', already documented by another author called Hawkins. Each of these consists of two instances of a sentence or paragraph, with one instance fitting well into its own context and the other not fitting its own context. He supposes that the one that appears not to fit is an insertion into an original, well structured text (which he calls proto-Matthew).
The last of these doublets is the angel's instruction to the women to tell the disciples to go to Galilee, and the similar instruction by Jesus himself in the next paragraph. After receiving the instruction once, it's surprising that the women would receive it again minutes later.
What I find almost inconsistent about Riley's theory is that on the one hand he says the description of the appearance in Galilee flows naturally from what comes before, but on the other hand he says that the appearance in Galilee appears to be edited in by someone for whom the mission to all nations and the close of the age is his main interest. Whereas the appearance of Jesus to the women looks like an addition, it's hard to know whether he thinks the original had an appearance in Galilee or not.
