I find your question intriguing and hope it is your desire, as is mine, for meaningful study and interaction regarding this subject. Please permit me your patience for just one moment if you would, as we examine how deep this little puddle you have posted, may reach.
Your post brings up several very important aspects of Scripture which have appeared to escape the notice of nearly the entirety of humanity.
I don't mean to appear to overly simplify, and it is not my intent to appear to insult your intelligence when I try to relate these things to explore the question, but one must start somewhere.
So
the question as to why there are so few "Jewish Christians" can be explained in one verse of Scripture.
Revelation 12:9
And the great dragon was cast out, that old serpent, called the Devil, and Satan, which
deceiveth the
whole world: he was cast out into the earth, and his angels were cast out with him.
Definition of WORLD
WORLD : the inhabitants of the earth :
the human race
Definition of WHOLE
WHOLE : complete or full :
not lacking or leaving out any part
Definition of DECEIVED
DECEIVED : to cause to
accept as true or valid what is false or invalid
What is the most interesting point of this verse is that, i
n the human mind,
IN THIS WORLD,
this verse applies to every human, but themselves.
Back to the question;
If one studies written Scripture without the encumbrance of embracing human dogma or tradition, one will find that
the "Jewish religion" and what we know as the "Christian religion" can never describe the "true servants", the "chosen people" of God.
Even without the overwhelming supporting historical evidence regarding the apostasy of these two religions, if the Scriptures ARE TRUTH, both MUST be excluded simply based upon the truth that;
-Both "religions" are a RECOGNIZED and ACCEPTED "part of human society".
Again, if one studies written Scripture
without the encumbrance of embracing human dogma, denominational explanations or tradition, one will find that
from Genesis to Revelation;
-ALL of the PROMISES and COVENANTS contained within Scripture were BESTOWED SOLELY UPON the HEBREWS. (Abraham; a Hebrew /12 Sons of Jacob/Israel; Hebrews(not Jews) /Moses; a Hebrew)
-God HIMSELF has never PERSONALLY declared himself TO BE the GOD OF ANY OTHER PEOPLE, than THE HEBREWS
Genesis 14
13 And there came one that had escaped, and told
Abram the Hebrew; for he dwelt in the plain of Mamre the Amorite, brother of Eshcol, and brother of Aner: and these were confederate with Abram.
Exodus 2
11 And it came to pass in those days, when Moses was grown, that he went out unto his brethren, and looked on their burdens: and
he spied an Egyptian smiting an Hebrew,
one of his brethren.
Exodus 9
1 Then
the Lord said unto Moses, Go in unto Pharaoh, and tell him, Thus saith
the Lord God of the Hebrews, Let
my people go, that they may serve me.
13 And
the Lord said unto Moses, Rise up early in the morning, and stand before Pharaoh, and say unto him,
Thus saith the Lord God of the Hebrews, Let
my people go, that they may serve me.
Therefore, the term Jewish Christianity would appear to better be described as "Hebrew Christianity".
Please understand I am not trying to find fault or split hairs, but if we truly hope to attain the salvation granted unto God's chosen people,
accurate terminology in our examination of this question
may serve to benefit those that truly fear God, and seek greater understanding.
So I suppose the question to ask now is;
What would be a "Hebrew Christian"?
May God bless,
Lee