I believe that all forms of Judaism and Christianity are compatible to a large extent. They are essentially brother faiths. The one major difference that they have, which is believing in Jesus as the Messiah, is all but erased in Messianic Judaism. The Bible calls for Christians and Jews to love each other.
Christianity by itself focuses in the Salvation of Yeshua, who wanted us to love G-d with all our heart, and to love our neighbor as much as ourself. It is the new covenant that completes Judaism as was promised by Him.
The roots of Christianity started out as just one of many sects of the ancient Hebrew religion that would be latter referred to as Judaism.The Pharisee Saul " Apostle of the Gentiles" who interpreted that non-Jews were not obligate to follow the laws passed from Moses, believing His grace was what matters. It allowed the spread of Christianity to advance much easier compared to what would later be Talmud Judaism.
In a sense Messianic Judaism is complet Judaism. The idea of Christianity being compatible to Jewish culture and tradition was never an issue. The reason why many people think that Christianity and Judaism are opposed is only because of the Talmud.
Acceptance of the Christian faith is actually quite simple. There are nuances in Christian beliefs, practices, and customs but at their core is a belief and trust in the deity of Jesus Christ as savior and messiah. It is an acceptance of Christ's forgiveness and grace.
Christianity and Judaism share many values and many things in common. Christianity was born out of Judaism. A messianic Jew need not, of necessity, forsake the many elements of Jewish culture and tradition that hold meaning to them. Accepting Christ is sufficient. The Bible tells us that Christ came to fulfill the law, not to abolish it. In once sense, many of the first Christians were Messianic Jews. Their culture and tradition can add to their worship experience and it is certainly compatible with their belief in Christ.
Chrisitian and Jewish culture, as in the value placed upon home, family, traditions, and the importance of God, are compatible. Where the two religions diverge is in the belief of Jesus Christ as the Messiah promised to the Jews. This, however, is a religious difference, which is another debate altogether. Many similar cultural values and traditions are embraced by both religions.
Messianic Judaism is an attempt to convert Jews to Christianity by luring them by using Jewish customs and traditions and using them to cover up the fact that Judaism and Christianity are entirely different. Christian groups will do anything in their power to convert Jews. Judaism and Christianity are two entirely different religions! "Messianic Judaism" is like "Islamic Buddhism". After the holocaust in which some six million Jews were murdered the Southern Baptists have no one else to convert other than a few million Jews? For all those who support "Messianic Judaism", respect Judaism by hearing what Judaism says about this movement and not what Christians think. How would many Christians feel if another religious movement used Christian symbols and customs to lure them into their faith. Religious groups should have good relationships with one another and this is not going to let that happen.
No, In the thirteen article of faith, G-d is one. Shema Ysrael Adonai Eloheinu Adonai Echad. Echad is one and cannot be render as three or complex unity. Furthermore, Messianic Judaism is Evangelical Christianity with a Jewish Flavour. It it a trick to convert Jews to Christianity. There is no substantial proof that Jesus/Yeshua was the Messiah. If you look the passage in context, they do not align with Messiah, they are taken out of context. Look at the book of Matthew, when it said that a text fulfils a prophecy, it is or taken out of context of misquote. I have been in the messianic movement, and honestly, they will say the Shema every week, but most of them, including myself were not Jewish at all.
The Sabbath is from Friday at dusk until Saturday at dusk. Christianity changed it to sunday (possibly to just set themselves apart from the jews) and Christians don't follow gods laws of the Sabbath. Christians think nothing of it working on the Sabbath. But jews (depending on which type of Judaism) are quite observant of the Sabbath and most follow gods laws of the sabbath