Now, I am not exactly sure I understand that statement either.
My question is, why would someone who was raised Jewish have
difficulty accepting the Messianic movement ("reconciling it with their
Jewish upbringing"), but have no problem with accepting Christianity?
It really boils down to the question of authority and stability I think.
The Messianic movement, while ostensibly Christian, has many radical elements within it that seek to undermine the Christian faith and who tend to almost mimic Judaism but do not actually come from a Jewish foundation. So, while claiming to not be Christian yet holding to the basic tenets of Christianity they come across as rather bizzarre.
Case in point: there is some nut called Michael Rood out there. He is not halachically Jewish, yet he claims he is a Messianic teacher. He came out of a cult called "The Way" who have a spiritual trail of wreckage and destroyed lives a mile long. He uses all the silly phrases like "Gentile thinking" and so forth to make out like he knows what he's talking about. But, the over-use of Jewish symbolism and odd phrases like the above screams "fake" to me. So, while the guy claims to be "Messianic" and speaking the truth about Jesus etc., the truth is that he has no authority whatsoever to do so and no actual legitimate connection to anything.
This is becoming all too common.
One thing I think myself and other Jewish Christians I know like is a decent genealogy. We like to know where things come from- it's a very Biblical idea, that. With a normal Christian Church, you can do a little history test and see how they are linked back to the founder, Jesus Christ. We can trace their teachings, minhagim and halacha (so to speak) if we care to. A lot of churches come through ok on this test, and some have no connection at all (eg. JWs, and this guy I mentioned above) When I see certain things done and taught that I can prove come from the foundation of the religion, I can have confidence in them. I think there is something instinctive in myself and the other Jews I know that says "if you're going to get on another bus make sure the driver has a license"
This is why I think ultimately, I can feel more comfortable in a church with ancient roots and traditions as a Jew then I can in one that merely adopts the appearance of being Jewish. I want a rock, not sand, as my foundation.
I could go on, but I'll end up preaching and although I will enjoy it I'm sure others here will not.
Please understand that I believe that the MJ movement has some very important things to do for the Church- but there are some spiritual/moral lessons they must learn as a movement first. This is why I support my local MJ congregation with prayer and good wishes (hardly any Jews in that group, BTW) They will come along in due time, as those who seek the Holy Spirit always do.