"In the beginning was the Word, and the Word was with God, and the Word was God. He was with God in the beginning. All things were made through Him..." -John 1:1-3a
It belongs to the person of Jesus, his essential person, to be the Eternal God. Jesus is no less Jesus throughout all of the countless eras existing before there was so much as a human conception of Israel.
amhn amhn legw umin prin abraam genesqai egw eimi
Before Abraham even comes into being, Jesus IS. Making Jewishness THE deciding factor of Jesus' being (and believe me, this seems to be every scholar's wet dream today) is nothing short of atheistic blindness. One might as well say that because Jesus walked the earth with corruptible flesh; his pre-existence must be defined according to the laws of corruptible flesh.
Jewishness is a mere cultural contingency. Culture cannot even be a static quality of humanity, for there is no situation wherein a human is not utterly free to renounce this or that culture in favor of another one. Thus we do not arrive at the irreducible person when we have gained a glimpse at his culture. This is an accidental quality, deserving of proper description and consideration but nonetheless accidental. In the case of Jesus, we can even lay aside these historical principles and simply bow before the fact that Jesus is not FIRST man, but very God of very God. The blind world and the blind christian intelligentsia can stick that in its pipe and smoke it.