One of the relatively frequent issues that are asked of me is about the practices of Messianic "Jewish" congregations. For instance, one of the congregants of Congregation Beth Chofesh Messianic Ministries invited me to their services, saying that when I see the service that I will see that they do things just like at my synagogue. Similarly, an attendee of Bat Zion Messianic Congregation said that their service certainly looks Jewish, such as their singing of Hebrew songs and wearing of kippahs. So this begs the question, "If these congregations do Jewish rituals and/or practices, aren't they Jewish?"
Often an analogy is helpful in understanding an issue, so allow me to give one involving my past. When I was a teenager, I attended public schools. One of the classes I took was Chorus. My teacher must have like my singing (for what reason I have no idea), because she recruited me to join a special Madrigal chorus that she organized. She taught the Madrigal chorus to sing a number of songs. However, traditional Madrigal music is from the Church. As such, she taught us to sing Ave Verum, a traditional Catholic church song. So here I was, a nice Jewish boy, singing a Catholic hymn! And to make it odder, the majority of the Madrigal chorus members were Jewish! Although we were all singing a Catholic song, essentially doing a Catholic practice, this did not change our religion. We were still Jewish, or Protestant, or Catholic, or whatever religion we were before we sang the song. Simply by engaging in a Catholic ritual did not make us Catholics, nor did it make the room we sang in a Catholic church. Similarly, engaging in Jewish ritual does not make the Messianic movement Jewish.
Going back to our start point, Messianic "Judaism" is not Judaism. It was created by the Church of England in the mid-1800's as a way of making Jews more comfortable in church and of bringing more Jews to Christianity. In fact, the movement's original name was Hebrew Christianity. "Messianic Judaism" did not become the popular name until the 1960's and 70's. The entire reason for engaging in Jewish practice is to put Jewish "clothes" on Christian beliefs. The Messianic movement can engage in any Jewish practice it wants but that does not change the fact that they are Christian congregations, just like my singing of a Catholic hymn did not change me from being a Jew.
In the cases of the aforementioned congregations, Beth Chofesh is part of the Assemblies of God movement (Pentecostal church) and Bat Zion is run by a graduate of Christ For the Nations Institute. Neither of them are Jewish. They (and all Messianic groups) hold Christian theological views such as believing in the Trinity while Judaism believes in a One, Non-Divisible G-d. They believe that Jesus was a god while Judaism holds to the Biblical view that G-d is not a man. They believe that the only way to atonement is by accepting Jesus while Judaism follows the Biblical view that there are multiple ways to atonement. The Messianic belief system is entirely Christian, not Jewish. No amount of Jewish practice or ritual can change this.
Ultimately, the Jewish practice of Messianic "Judaism" is a cover for Christian theology and does not make the movement any more Jewish than the mother churches and pastors that created these congregations.