The four Hebrew letters that represent God`s name in the Old Testament (hebrew Scriptures ) the tetragrammaton do not appear in the New Testament the Christian Greek Scriptures.
Nor do any equivalent four letter Greek letters translated from the Hebrew , the Tetragrammaton exist in the New Testament,to represent the name of God. Their just not their.
Those four consonants , translated in english from Hebrew as either JHVH or YHWH , contained in the Old Testament are their because they exist in the Old Testament Hebrew sources.
And so the name Jehovah / Yahweh (preferably ) is warranted in the Old Testament .
But the same cannot be said about that name for God or any other name for God in the new testament.because the source of these texts do not contain those four letters either in Greek or Hebrew to warrant their inclusion in the New Testament,
Neither Jesus , the Apostles ,nor his disciples ever used the " word" Jehovah in the New testament /Christian Greek Scriptures
Not one of them ever used that word Jehovah /Yahweh , not one of them.
Yet in the Christian Greek Scriptures the New Testament plainly states that the name of JESUS is to be "exalted above" every other name in Heaven , on Earth , and under the Earth.
The Bible clearly shows that followers of Jesdus Christ were by
" Divine providence " to be called Christians ( not Jehovahs Witnesses )
That is from the mouth of God., if you put your faith in the Bible.and not a man made organization of the late 1800`s ,when so many religions began.