“But that the dead are raised, even Moses showed, in the place concerning the Bush, when he calls the Lord, the God of Abraham, and the God of Isaac, and the God of Jacob. Now he is not the God of the dead, but of the living, for all live to him.”
Jesus then dealt with the Torah's basis for the resurrection. In Exodus 3:6 Moses had spoken of God as ‘the God of Abraham, Isaac and Jacob'. But, says Jesus, God cannot be the God of the dead, for to be someone's God they must be able to appreciate His Godhood. Thus He can only be the God of the living. That must mean that all who have truly known God, and have entered into covenant relationship with Him, must have life in Him, and are indeed seen by Him as having such life. That being so resurrection to life for His own necessarily follows so that they can fully enjoy God in this way.
Putting it another way. The dead do not praise God (Psalms 88:10; Psalms 115:7). He is not their God. So if God is the God of Abraham, Isaac and Jacob they must in some way be enjoying life, even though they have apparently died. For He is the God only of the living. There may also be solidly included in this the significance of the covenant relationship with God which was indicated by the title, ‘the God of Abraham, Isaac and Jacob'. God could not be seen as being in a covenant relationship, which was a deeper one than that of marriage, with those who were no more. Thus they must in some way have been alive when God spoke these words. Some of the Psalmists also actually reveal a vague belief in an afterlife on the same basis, that they could not believe that their positive and glorious relationship with God, which was in such contrast with those whose minds were set on earthly things, could cease on death (e.g. Psalms 16:9-11; Psalms 17:15; Psalms 23:6; Psalms 49:15; Psalms 73:24, see its whole context; Psalms 139:7-12; Psalms 139:24).
It will be noted that this teaching does away with any possible belief in reincarnation. In Jesus' eyes there was no thought that any of them could be reincarnated. His argument indicated the opposite. Thus it is impossible to take Jesus seriously and believe in reincarnation.
‘In the Bush.' In Jesus' day the Old Testament was split up into sections each of which had a heading. This was probably for the purpose of synagogue worship. The section headed ‘the Bush' contained Exodus 3.