And concerning the resurrection of the dead, have you not read what was said to you by God: “I am the God of Abraham and the God of Isaac and the God of Jacob”? He is not God of the dead but of the living.
Here is the question: When Jesus says, “He is not God of the dead, but of the living,” does he mean that Abraham, Isaac, and Jacob are alive somewhere, awaiting resurrection? Those who maintain that the New Testament teaches at least a conscious intermediate state in the presence of Jesus will often find support for their view in this passage.
These two verses are an argument for resurrection directed against the Sadducees, who rejected all belief in an afterlife and for whom only the Torah was authoritative.
If Jesus means, therefore, that the patriarchs are currently alive and conscious, he must believe that they have already been raised, otherwise it is an argument not for resurrection but merely for the continued existence of the dead—as shades in Sheol, for example. With the exception of the anomalous account of the raising of the dead from their tombs in Matthew 27:52-53, this would run contrary to the broad biblical understanding of resurrection as an end of the age event—though what is meant by “end of the age” is another matter. In the New Testament Jesus is the “first fruits of those who have fallen asleep” (1 Cor. 15:20), the “firstborn from the dead” (Col. 1:18).
The quotation is from the story of Moses’ encounter with God at the burning bush (Ex. 3:6; cf. Mk. 12:26). The significance of the claim to be the God of Abraham, Isaac and Jacob is specifically that YHWH remains faithful to the promise made to the patriarchs that he will bring his people into the land that he has given them. This is made clear by what directly follows:
Then the Lord said, “I have surely seen the affliction of my people who are in Egypt and have heard their cry because of their taskmasters. I know their sufferings, and I have come down to deliver them out of the hand of the Egyptians and to bring them up out of that land to a good and broad land, a land flowing with milk and honey, to the place of the Canaanites, the Hittites, the Amorites, the Perizzites, the Hivites, and the Jebusites. (Ex. 3:7-8)
I would suggest that Jesus has a similar story in view: at this time of extreme eschatological crisis God will remain faithful to his promise to the patriarchs and will deliver his people from their bondage—a redemption which this time will include in some manner the resurrection of the dead.
The quotation from Exodus 3:6, therefore, means that the God of Abraham, Isaac, and Jacob is committed to the future life of his people: he is God not of the dead but of the living. The specific thought is simply that the patriarchs will also be raised in the coming resurrection.
I should point out that belief in the continuing existence of the patriarchs is found in 4 Maccabees 7:19 and 16:25. Faithful Jews who die under torture will live, as Abraham, Isaac and Jacob live. Two things need to be taken into account, however. First, these martyrs expect to be raised from dead (cf. 2 Macc. 7:9, 14), not simply to enter an afterlife. Secondly, the reference is always to the patriarchs. Why this particular group? Why not other righteous Jews? Arguably it is the symbolic significance of the patriarchs that is at issue here rather than any more literal belief in their continued life.