That is one angle to look at it, and it is the angle that, from the standpoint of Judaism, makes Christianity look problematic.
On the other hand, though, orthodox Christianity does teach that Jesus is God (specifically, the second person of the trinity) made flesh. Now, you and I disagree about whether God is one person or three, and we disagree about whether God became man. But the God we are talking about -- the God who we agree acts in the Hebrew scriptures, and the God Christians believe became incarnate in Jesus -- is one and the same. We disagree about God's nature, and about what He did, but we are still talking about the same Being.
Let me give an analogy. Take an average liberal and an average conservative. Now, they would hold profoundly different opinions about Bill Clinton as a man, and what sort of job he did. But they would agree that he was President of the United States from 1993 to 2001.
Excellent point. So why is it that every Jew who comes to that realization (that Jesus is YHVH manifest in the flesh) is immediately rejected by the whole of Judaism and is no longer recognized by Jews as being a Jew?
Or do you believe that there is such an animal as a Jew for Jesus, or a Messianic Jew?
And if there is, then why is Israel so adamant about prohibiting the Jews for Jesus people from proselytizing Jews in Israel? Aren't they (according to your definition) just Jews who believe in Jesus?
You can be an atheist Jew, you can be a Zen Bhuddist Jew, but it seems that you can't be a Christian Jew? Am I wrong?