First. In general, Christians don't "believe that Jesus is 'YHWH'." They believe He is "God".
So your major premise is false. (And being false, it renders the remainder of your post invalid as well.)
Well Howdy Mr Parker, or should I call you sir? Two pompous, overly combative opponents both wishing to pontificate. This could be fun.
For starters Sir, I clearly stated, "Many believe that Jesus is YHVH". My statement is fact, not premise as some in this thread indeed believe that Jesus is YHVH as I am assuming you have found out. If not, I can locate a link in the Lounge which this OP originated.
That you add "Christians don't believe Jesus is YHWH", infers that you either didn't take the time to think of the ramifications of your statement or you were simply ignorant of the implications.
For starters, if a Christian believes that Jesus was YHVH or as you prefer, YHWH, does that belief then disqualify them as Christians? Thus, since they don't believe as you believe, they truly are not Christians. Or do you simply live in a glass tower and rule over scriptures in your own ivory throne?
See, I can return the banter just as readily. Kinda puts you in battle mode doesn't it? But in all honesty, it drains me and leaves me empty, and feeling horrible at the end of the day. As Christians, we are to be patient with one another and where possible, uplift them. You shall hear no more banter from me. What did Jesus say?
John 13:35 By this shall all men know that ye are my disciples, if ye have love one to another.
Please review 1 Cor 15 for the topic of love.
And, just as an excursus, it has been my experience that people who insist on using the names Yahweh and Yeshua are very often posers who are attempting to sound erudite and to appear to be in possession of some deep knowledge with which they can impress and astound us all. (yawn) And it has been my experience also that they consistently lack the theological training to support their assumed role. I'm not saying that's you; I'm just saying that has been my experience.
I am truly sorry that has been your experience. I do not share that experience with you. Hopefully our exchange will edify and we can learn from each other.
But as to the word "LORD" in the OT:
When you see LORD (all caps) it is translating "YHWH ELOHIM" or "ELOHIM". (Elohim is the most often word used in the OT to refer to God; it is found 2602 times in the Hebrew Bible ) It comes from the use of the Greek word "KURIOS" in the Septuagint (LXX) which was the most commonly used scriptures at the time of Jesus and in which Yahweh Elohim was translated as Kurios..
The Capitalizing of the word LORD" in modern translations reflects the LXX usage and is confined to the Old Testament.
By far, you have a greater grasp on the Greek language than I. When I study the OT, I do so in in the Hebrew and the commentaries I use also utilize the Hebrew.
Years ago I audited an OT Theology class and I learned a great deal. I claim to be no expert let alone a scholar. One of the books I purchased was Ancieint Near East texts, by Pritchard. Amazing compilation of translations from the near east.
Did you know that what we translate as El and Elohim aren't actually Hebrew words? Yet we find them being used many times in the Hebrew texts.
In the English, both EL and Elohim are translated as God and our modern versions do not give their meanings justice. El is singular and denotes the head of the pantheon. When El is used in the singular, I do believe it is pointing to the idea of a stand alone god. When used in the plural (Elohim), it is encompassing divine authority over the pantheon. In simple terms, El the warrior while Elohim conquered the nations.
We see this in the Hebrew OT as El Shaddia, or "God Almighty" aka the good shepherd as denoted by the languages pictorial roots. (Genesis 28:3 )
And still so...
Psalms 110:1 <<A Psalm of David.>> The LORD (YHVH) said unto my Lord (Adoni), Sit thou at my right hand, until I make thine enemies thy footstool.
Or as we also see
Deuteronomy 10:17 For the LORD (YHVH) your God (Elohim) is God (Elohim) of gods (Elohim), and Lord (adoni) of lords (adoni), a great God (Elohim), a mighty, and a terrible, which regardeth not persons, nor taketh reward:
Again, I am not familiar with the rendering of the Septuagint on these words, but we should both be able to learn from the original Hebrew.
Theologically:
There is one God Who is Father, Son and Holy Spirit, Trinity in unity. In the New Testament, the words "Lord" and "God" are used to refer to that one, triune God.
And example is Elizabeth's greeting of Mary at Luke 1:43 “But why is this granted to me,(Elizabeth) that the mother (Mary) of my Lord (Jesus) should come to me? In this question, Elizabeth identifies Jesus as God by referring to Him as "my Lord."
My intent is not to get into the finer points of the trinity. Textually, "Lord" in the greek had several meaning depending upon it's usage. While I agree with your rendering of Luke 1:43, as well as many other passages, the word was not exclusive to the Jews.
Matthew 16:16-17 And Simon Peter answered and said, Thou art the Christ, the Son of the living God. And Jesus answered and said unto him, Blessed art thou, Simon Barjona: for flesh and blood hath not revealed it unto thee, but my Father which is in heaven.
What we see here is that God the Father had revealed to Peter that Jesus was not only Lord, as Peter had called him in the past ( Matthew 14:30 ), but that Jesus was the Messiah (Christ) as well.
John 1:1 specifically and unequivocally states that the Word who became flesh (as Jesus of Nazareth) is God. The word used for "God" is the Greek "THEOS" not the Hebrew YHWH or Elohim or YHWH Elohim or El or Adoni or any of the many other names of God used by the Hebrews. And, at the time of Jesus, the Jews would commonly refer to God as "the Name" so as to avoid taking God's name in vain.
And, yes, I do have the formal theological training.
iakov the fool
The text does not say the Word "who" became flesh... it states that the word was made flesh.
We know from Genesis 1, it is the idea of Elohim who creates and makes, and he shows his creative authority through his words. Words are very powerful, so we ought to be careful how we use them. James even gives us a warning of our tongue.
But what we clearly see is that it is God's Word that makes... and that Word was made flesh. What we see is the second Adam.,, God is doing something new in creation.
John 1:14 And the Word was made flesh, and dwelt (tabernacle) among us, (and we beheld his glory, the glory as of the only begotten of the Father,) full of grace and truth.