Now he is not God of the dead, but of the living, for all live to him. (Luke 20:38 ESV)
The Sadducees were a group of religious leaders that did not believe in the after life. One day in a bid to discount and humiliate Christ they put him to question. Like their contemporaries, the Pharisees, they concocted a strange rhetorical situation as an attempt to determine Jesus’ traditional affiliation and political leaning. Par for the course he proved that the people did not have their mind or hearts set on the things of God.
Those who belief on Jesus for their salvation are brought into a new life. They have rejected death. They have left behind sin. Not because they are perfect but because Jesus has taken sin from them based on their faith in his sacrificial power and blameless life.
God created men for life, love, and relationship with Him. To be in union with Him is to enjoy eternal life. God is the God of life. That all sounds perfectly strange and seemingly beyond comprehension, but in a way that is what makes the majesty of it that much more wonderful.