"He will Never Taste Death" (8:48-50)
The belief of Jesus' critics that he "has a demon" (8:48)—that is, Jesus is willingly or unwillingly possessed by a demon—is confirmed for his critics by Jesus' claim that "if anyone keeps my word, he will never see death" (8:51). From the post-resurrection perspective, Jesus is speaking about eternal life (3:15, 5:38, 6:54, 68, 10:28, 17:2), as manifest by the resuscitation of Lazarus (Jn. 11:1-57), and the resurrection of Jesus (Jn. 20-21). But neither of these events has happened at this point, and the Jews are confused. Thinking Jesus is making the claim that his disciples will never die at all, they respond: "Now we know that you have a demon! Abraham died, as did the prophets, yet you say, 'If anyone keeps my word, he will never taste death'" (8:52). Paradoxically, however, first century Jewish tradition actually maintained that Enoch (Gen. 5:21), Elijah (2 Kgs. 2:11), and perhaps Moses (Assumption of Moses) never "tasted death." The Jews thus see Jesus as claiming to be greater than Abraham and the other prophets—"who do you make yourself out to be?" (8:53)—a preposterous claim from their perspective.
Jesus' response is simply that he does not glorify himself by these claims, but is glorified by both the Father (8:54), and the prophets: "Your father Abraham rejoiced that he would see my day. He saw it and was glad" (8:56). This is probably an allusion to the covenant of God in Genesis 12:1-3, where God promises that "in you [Abraham] all the families of the earth shall be blessed" (Gen. 12:3), and Genesis 17:17. However, there were many near contemporary Jewish traditions that described Abraham receiving a vision of the Messianic Age, which to Christians would mean seeing the day of Jesus.
The Jews, however, wondered how Jesus could claim to know Abraham's thoughts:
So the Jews said to him, "You are not yet fifty years old, and have you seen Abraham?" Jesus said to them, "Truly, truly, I say to you, before Abraham was, I am." So they picked up stones to throw at him, but Jesus hid himself and went out of the temple (8:57-59).
What did the Jews at the temple understand Jesus to be saying, that would provoke them to try to stone him to death?
The Name of God in Israelite Tradition
To answer this question we need to digress a bit to examine first century Jewish name theology. In the Old Testament traditions, God revealed his personal name, YHWH, to Moses on Mount Sinai (Ex. 3:15), claiming that before the time of Moses, God had not been known by his true name (Ex. 6:3). This is expressly stated in Exodus: "I [God] appeared to Abraham, to Isaac and to Jacob, as God Almighty (ʾel šaddāy), but by my name YHWH I did not make myself known to them" (Ex. 6:3). This divine name is generally translated as LORD (in small capital letters) in English translations of the Bible, and is generally transliterated as Jehovah (voweling YHWH as YeHoW/VaH). Israel thereafter made a covenant with YHWH, to worship only "YHWH your God."
The importance of this divine name is found throughout the Hebrew Bible. Israel is consistently commanded to "call upon the name of YHWH." Likewise, they are to glorify or praise the name of YHWH. Hymns praising the name YHWH are found throughout the Psalms. Many Israelite names are theophoric, and include the name YHWH in one form or another. The Divine Name is also found in non-biblical sources from ancient Israel: inscriptions, letters, and seals. As far as we can tell, there was originally no prohibition against writing or saying the name YHWH in ancient Israel; only against blaspheming or misusing the name, or falsely claiming to speak in the name of YHWH (Ex. 20:7; Dt. 5:11).
A major transformation in Israelite Name theology, however, occurred in the Second Temple period between the conclusion of the Hebrew Bible and the age of Jesus. Restrictions on the ritual writing and pronunciation of the name YHWH had developed by at least the third century before Christ. In place of actually pronouncing the name YHWH when reading scriptures or praying, Jews increasing said ădōnāy in Hebrew, translated as kurios in Greek, both meaning simply "lord." (Hence the English use of LORD to render the divine name.)
In the Hebrew biblical manuscripts from this period they often wrote the name of God in the Paleo-Hebrew script indicating its special status and unique pronunciation. By the time of Jesus many Jews also began to simply say ha-šēm ("the Name" [of God]) when they came across the name YHWH in reading a text. This practice can already be found in Leviticus 24:11, 16 where an Israelite is described as blaspheming "the Name" (ha-šēm), meaning the name YHWH. These practices still continue among Orthodox Jews today, who, when reading aloud or speaking the name YHWH, will say ădōnāy (lord), ha-šēm (the name), or vocally spell the name, saying yôd-hê-vāv-hê.