First of all, the other answerers were right. "messianics" are not Jewish. Most of them never WERE Jewish–they are Christians who get a kick out of "playing" Jewish, while at the same time gutting Judaism of its true beauty and meaning. They don’t understand why we object to their disrespectful behavior…and *I* don’t understand WHY they don’t understand!
Having said that, they make a really sad stab at doing things the same way, but from what I’ve seen, their efforts are fairly laughable.
My daughter attended a Jewish school, and they showed the kids a tape of a messianic "worship service", in an attempt to educate the kids about Christian attempts to deceive Jews. The school administration needn’t have worried about the kids–because the service was so strange as to be laughable. That’s what my daughter told me–that the whole assembly was actually laughing, watching messianic attempts to emulate Jews.
From personal experience, I’ve seen messianics trying to keep Jewish traditions and having absolutely no idea what they were doing. It’s painful to watch their profane trampling of sacred traditions.
And of course, there are many of our traditions that they PURPOSELY twist and change. When I was converting to Judaism, I bumped into a few messianics who tried very hard to convince me that they were good Jews–but who wanted only to bring me to Jesus. Before I realized who they were, I accepted materials from them, like tapes of prayers in Hebrew, etc. I listened to these tapes, and even I–a new convert-to-be–could tell that the blessings sounded off, as if whoever had made the tape didn’t know what they were doing. It took me awhile to realize why, but when I got to the "blessing for the new covenant", I realized why.
The messianics still denied that they believed in Jesus. They had infiltrated the congregation, were missionizing a lot, and had the nerve to LIE about their man-god. But then, their hero, Paul, said that he made himself into "all things" so that he could reach all men. So I guess that lying is a messianic tradition.
Sorry–I have no respect for them. Give me a good old fashioned Christian who is strong in his/her beliefs and has good moral character, and we’ll get along fine. But messianics aren’t honest–even with themselves!–and their attempts to ‘copy’ our traditions are pathetic.