Thomas,
It has nothing to do with identity grabbing as you state/put it.
Let me explain:
If I were to apply for citizenship of Portugal or America and is granted citizenship, what do I become?
......a Portugese or an American.
So if I apply for citizenship of Israel, what do I become if granted?
......an Israelite.
If you want me to, I can show you Bionically why you are not supposed to call yourself a Christian:
Eph 2:11 Therefore, remember your former state: you
Gentiles by birth - called the Uncircumcised by those who, merely because of an operation on their flesh, are called the Circumcised -
Eph 2:12 at that time
had no Messiah.
You were estranged from the national life of Isra'el.
You were foreigners to the covenants embodying God's promise. You were in this world without hope and
without God.
Eph 2:13
But now, you who were once far off have been brought near through the shedding of the Messiah's blood.
Eph 2:14 For he himself is our shalom - he has made us both one and has broken down the m'chitzah which divided us
Eph 2:15 by destroying in his own body the enmity occasioned by the Torah, with its commands set forth in the form of ordinances. He did this in order to create in union with himself from the two groups
a single new humanity and thus make shalom,
Eph 2:16 and in order to reconcile to God both in a single body by being executed on a stake as a criminal and thus in himself killing that enmity.
Eph 2:17 Also, when he came, he announced as Good News shalom to you far off and shalom to those nearby,
Eph 2:18 news that through him we both have access in one Spirit to the Father.
Eph 2:19
So then, you are no longer foreigners and strangers. On the contrary,
you are fellow-citizens with God's people and members of God's family.
Eph 2:20 You have been built on the foundation of the emissaries and the prophets,
with the cornerstone being Yeshua the Messiah himself.
Eph 2:21 In union with him the whole building is held together, and it is growing into a holy temple in union with the Lord.
Eph 2:22 Yes, in union with him, you yourselves are being built together into a spiritual dwelling-place for God!
Hope that helped?