So what you're saying is that your god says things that he doesn't mean? Or at the very least, he doesn't make clear what he means. Which is sort of self-defeating, since the people in the time the bible was written were notorious for not being very smart, as a population (thanks to the rulers of their day, who kept education for the elite. The average person was busy working in order to stay alive). Again, either way you choose to look at that, you're going to either have to completely disregard one portion of it. My argument would be that the "until all is accomplished" is INCLUDING his supposed self-proclaimed second coming, which makes sense in the greater context of the bible.
For it to pass away at all is telling concerning the job Jesus came to do. Actually, we are both right. Jesus talked about fulfilling all of the Law and the Prophets, and there are many prophecies concerning the Messiah that are yet to be fulffilled. However concerning the Law and all the commands there, Jesus lived it out and was completely obedient. With that, He became the perfect sacrifice on behalf of mankind. He took all the judgment onto Himself and died, as the judgment for breaking the Law is ultimately death. So in essence, Jesus died our death, and anyone who trusts on Him, has died with Him on the cross. (This is what baptism is truly about.) This means anyone found in Jesus, has already died to the Law (all the commands). For us, the Law has passed away, but it does remain for those who aren't in Christ. So we are both right, in that the Law does remain right now, but not to those who have already died to it in Jesus. Even when Jesus comes back as you mentioned, nothing is going to change for Christians when He returns. Our sins are forgiven right now, and forever. There's no need to go back to the Law, because Jesus completed the commands and lived the obedient life on our behalf. So the life we live now, going back to my OP and the "foundation of a christian statement", comes from Jesus' obedience and nature. Does that make sense?
Of course, again you could say it's just my interpretation. Yet let me give you some things written in Matthew that kind of confirms that christians aren't supposed to perform the Law. Look at the situation concerning the transfiguration of Jesus. On the mountain Moses and Elijah appeared with Jesus, and begin talking with Him. Moses represented the Law (as he was the one who gave it, and the laws are usually synonymous with Moses' name) and Elijah represented the prophets. Peter offered to build three tabernacles (perhaps alters, I don't know). One for Him, Moses and Elijah. Then a cloud covers them and the Father tells Peter that Jesus is His beloved Son and to hear Him. This tells us that Jesus superceded both the Law and the Prophets. Putting together that Jesus said the Law would pass away and that He came to fulfill it, this shows us that our righteousness would come from Him and not the Ten Commandments and other laws.
That's not enough for you? There's another message in this account that's hidden here. On the mount of transfiguration, Jesus took with Him only three disciples. (Peter, James, and John) This is a lost art in today's society, but back then people knew their names had meaning. In this case, these three names have a very significant meaning. Peter's name (Cephas in aramiac) as most might know, means "stone". James is an off shoot of the name "Jacob" which means "Supplanter or to supplant". John's name means "God is gracious". So when you put them together, it reads like "The stone has been supplanted by God's grace". We know the Ten Commndments were written on tablets of stone, so we could say the stone in this hidden message represents the Laws of the OT. It's easy to see why this hidden message should be read in this way, when you look at what God the Father said to Peter, about hearing Jesus. So that's my take on the whole deal.