Q. In Deuteronomy 32:39,40 Yahweh says, “I live forever”, and in Psalms 102:27 David says “Your years will never end”. If Yahweh cannot die, then how can Yahshua be Yahweh and die on the stake?
A. Several of the anti-missionary’s allegations here could indeed prove worrisome, if proven correct. Closer examination of the Scriptures in question; specifically Deuteronomy 32:39,40, however, reveals unsubstantiated claims based on “selective scholarship” or partial quotations of Scriptures which actually disprove the theory when examined in their entirety.
Deut. 32:39 See now that I, I am He, and there is no deity beside Me. I have put to death and I make alive. I have wounded and I heal, and from My hand no one delivers.  For I lift My Hand to heaven, and say, ‘I live forever’.
The Hebrew reads “REUH ATAH KI ANI ANI WHO VEYN ELOHIM EMADI”, or “I, I”, or “I even I”, or “I also I”, with no comma or hyphen in the Hebrew, referring to the two primary faces of Yahweh (Father and preexistent Son). Now let’s take a look at several other verses where the phrase, ANI ANI appears.
Isa. 43:25 I, I (ANI ANI) am He that blots out your transgressions for My own sake, and remember your sins no more.
Isa. 51:9l Awake, awake, put on strength, O Arm of Yahweh. Awake as in days of old, everlasting generations....  I, I (ANI ANI) am He that comforts you: who art thou, that thou shouldest be afraid of a Man that shall die, and of the Son of Man which shall be made as grass?
Who is this Son of Man, spoken of by the prophet, who shall die and be made as grass? The answer is found in:
Zech. 13:7 O sword, awake against My Shepherd, against the Man who is My Fellow declares Yahweh of hosts. Smite the Shepherd and let the sheep be scattered. But I shall turn My Hand upon the little ones.
The Hebrew of this verse reads “CHEREV OORI AL ROAEHI VEAL GEVEER AMITI NEOOM YAHWEH TSAVAOT. NAKAH ‘ET HAROAEH”, or “Sword rise on My Shepherd, the Man, My Equal Companion, declares Yahweh of hosts. Smite ALEPH TAW the Shepherd.”
In the Hebrew it is clear to see that this smitten Shepherd (the same One put to death in Deuteronomy 32:29) is the equal of Yahweh, as part of the ELOHIM ECHAD of Israel. The Father aspect of Yahweh, “who alone is immortal and who lives in unapproachable light, whom no one has seen or can see” (1 Timothy 6:16) cannot die, but the YACHID or only begotten Son who comes forth from the bosom of the Father (John 16:28; 3:13) and who is imbued with the very nature of Yahweh (called the QNOMA in the Aramaic Peshitta—see John 1:3 and Colossians 1:17 in Aramaic) can, because He has taken on the form of a Man, hence the limitations of human flesh.
Psa. 22:16 For dogs have surrounded Me; a crowd of evil ones have encircled Me, piercing My hands and My feet.  I count all My bones. They look, they stare at Me.  They divide my garments among them, and for my raiment they cast lots...  Deliver My life from the sword, My Only (YACHID) from the power of the dog. (ISR Scriptures)
Zech. 12:10b (Yahweh speaking) And they shall look on Me whom they have pierced, and they shall mourn for Him as One mourns for His Only (YACHID) Son. And they shall be in bitterness over Him as over the Firstborn. (ISR)
Luke 24:38 And He said to them, “Why are you troubled and why do doubts arise in your hearts?  See My hands and My feet, that it is I Myself. Handle Me and see, for a spirit does not have flesh and bones as you see I have....  Thus it has been written, and so it was necessary for the Messiah to suffer and to rise again from the dead the third day.
Job 19:25 (KJV) For I know that my Redeemer lives (present tense), and that He shall stand at the latter day upon the earth:  And though after my skin worms destroy this body, yet in my flesh shall I see Elohim:  Whom I shall see for myself, and my eyes shall behold, and not another...
Job 19:25 (ISR Scriptures) For I know that MY REDEEMER LIVES, and AS THE ‘LAST’ SHALL RISE OVER THE DUST;  and after my skin has been struck off, then in my flesh I shall see Eloah,  whom I myself shall see on my side, and not a stranger....  But you should say, “Why do we persecute Him, seeing the root of the matter has been found in me?”  Fear the sword yourselves, for wrath brings the punishment of the sword, so that you know there is a judgment.
The Name of Yahweh defines Him — I was, I am, I will be — existence in all three tenses. He is eternal. The immortal cannot die, thus the fullness of Elohim could not die on the stake, but only the human body which He poured Himself into (Philippians 2:8) and the flesh which was imbued with His Spirit and Divine Nature (John 1:3 and Colossians 1:17 in Aramaic).