Jehovah’s Witnesses theology centers on the Deity referred to in the Old Testament by the name of Jehovah—Jesus Christ being one of the main players in that elaborately constructed theology (perhaps the main player), but not the same as Jehovah. It hinges on the assumption that Jehovah and Jesus are two different beings. That assumption is so central to JW theology that if it can be proved conclusively from the Bible that Jesus Christ is in fact the same as Jehovah, it has the effect of destroying their elaborately constructed theology from the foundation up. It causes the whole structure to come crashing down. The biblical proof that Jesus of the New Testament is in fact the same as Jehovah of the Old Testament, however, is indisputable. Here are some references:
John 8:
58 Jesus said unto them, Verily, verily I say unto you, Before Abraham was, I am.
59 Then took they up stones to cast at him: but Jesus hid himself, and went out of the temple …
The expression “I am” is the standard trademark of Jehovah in the Old Testament, with which the Jews were familiar; hence their taking offence at His remark, and trying to stone Him, implying that He had committed blasphemy by identifying Himself with Jehovah—and notice that Jesus does not deny the accusation. Here Jesus informs us that He is in fact Jehovah.
1 Corinthians 10:
4 And [the Israelites who came out of Egypt] did all drink the same spiritual drink: for they drank of that spiritual rock that followed them: and that rock was Christ.
The “Rock” referred to by Paul in the Old Testament signified Jehovah, thus implying that Jesus of the New Testament is the same as Jehovah. In the following quotes, given from the KJV, “LORD” is used as a direct translation of the Hebrew “Jehovah”:
Isaiah 43:
3 For I am the LORD thy God, the Holy One of Israel, thy Saviour …
This verse becomes more meaningful in the light of the quotations from Zechariah given below.
Zechariah 11:
12 And I said unto them, If ye think good, give me my price; and if not, forbear. So they weighed for my price thirty pieces of silver.
13 And the LORD [Jehovah] said unto me, cast it unto the potter: a goodly price that I [Jehovah] was priced at of them …
According to Matthew 27:9, this verse is a prophecy of the betrayal of Jesus Christ; yet it is Jehovah who is speaking, thus identifying Jesus with Jehovah.
Zechariah 12:
8 In that day shall the LORD defend the inhabitants of Jerusalem; and he that is feeble among them at that day shall be as David; and the house of David shall be as God, as the angel of the LORD before them.
9 And it shall come to pass in that day, that I [LORD, Jehovah] will seek to destroy all nations that shall come against Jerusalem.
10 And I [LORD, Jehovah] will pour upon the house of David, and upon the inhabitants of Jerusalem, the spirit of grace and of supplications: and they shall look upon me [Jehovah] whom they have pierced, and they shall mourn for him …
By all accounts, this is an indisputable prophecy of the Second Coming of the Savior (see Revelation 1:7); and the identification of Jesus with Jehovah is undeniable. Jesus [Jehovah] is returning as the “Savior” of the Jews at His Second Coming in the last days, and they shall look upon Him Whom they have pierced.
Zechariah 14:
3 Then shall the LORD go forth, and fight against those nations, as when he fought in the day of battle.
4 And his [LORD, Jehovah’s] feet shall stand in that day upon the mount of Olives, which is before Jerusalem on the east, and the mount of Olives shall cleave in twain in the midst thereof toward the east and toward the west … (Zechariah 14:3-4.)
Again, this is an indisputable prophecy of the Second Coming of the Savior, identifying Jesus with Jehovah.
Jeremiah 23:
5 Behold, the days come, saith the Lord, that I will raise up unto David a righteous branch, and a King shall reign and prosper, and shall execute judgement and justice in the earth.
6 In his days Judah shall be saved, and Israel shall dwell safely: and this is his name whereby he shall be called, THE LORD OUR RIGHTEOUSNESS.
This is another obvious and well-known prophecy of the coming of the Savior, who is named here THE LORD OUR RIGHTEOUSNESS! “LORD” is a translation of Jehovah. In other words, this future king, the Savior, Jesus Christ, who will be born of the house of David, and will reign over Israel, shall be called JEHOVAH OUR RIGHTEOUSNESS! I think that these references are pretty conclusive that Jesus of the New Testament is the same as Jehovah of the Old Testament. It presents a serious challenge to JW theology which I don’t think they have an answer for.