He is not the God of the dead, but of the living, for to him all are alive

Luke 20:27-47
But those who are considered worthy of taking part in the age to come and in the resurrection from the dead will neither marry nor be given in marriage, and they can no longer die; for they are like the angels. They are God’s children, since they are children of the resurrection.  Moses calls the Lord ‘the God of Abraham, and the God of Isaac, and the God of Jacob.’ He is not the God of the dead, but of the living, for to him all are alive.
David calls him ‘Lord.’ How then can he be his son?
Beware of the teachers of the law. They like to walk around in flowing robes and love to be greeted with respect in the marketplaces and have the most important seats in the synagogues and the places of honor at banquets. They devour widows’ houses and for a show make lengthy prayers. These men will be punished most severely.
Why?
Resurrection from the dead like angel neither marry not be given in marriage, so Sadducee asked questions were meaningless.
God is God of Abraham, Isaac, and Jacob in different times so God is not the God of the dead, but of the living, God is existing forever.
Beware of the teachers of the law, they like the outside honor and feature, but their heart is dark and ugly, they will be punished most severely.
How?
Let me have the perspective of the future with God's view, not only limited on the matter of this world.