It is impossible to learn in depth about all the lives of our physical world; it is much harder to learn about something which is beyond what the eyes can see and the mind can envisage. The question about whether there is a life after death, that the Pharisees and the Sadducees asked Jesus, did not come from their goodwill.
First, the horror of war and the bitterness of living exiled in foreign lands, somehow influenced their way of life, and that affected their way of translating the Law of Moses. Both groups loved Moses and had great respect for the Law, and yet each had its own way of interpreting the Law.
Second, the Sadducees were more on doctrinal. For them the text from the Pentateuch was the main source of interpretation of the law. For the Pharisees, both the Pentateuch and the oral traditions were acceptable. Probably the Romans ruled with brutality, and that made an impact on the Sadducees' way of viewing the reality of our physical death. The Pharisees saw the cruelty of life was man's arrogance. They distrusted men's goodness and turned to God. For them God has the final words: the resurrection, and reward or punishment after death.
Third, the Pharisees claimed that they had the authority to interpret the Law; while the Sadducees controlled wealth and enjoyed positions within the Temple. The chief priest and high priest were Sadducees, and they had the majority of seats in the Sanhedrin. The Sadducees had set aside differences and were united with the Pharisees to harm Jesus because He often attacked their practices in the Temple. Jesus confirmed to the Pharisees and Sadducees that eternal life is given on God's terms.
First, those who followed God's way were judged worthy of eternal life. They died no more but live forever in God's kingdom;
Second, what our physical body needs in this world, and what our spiritual life needs now and in the life to come; are not the same;
Third, physical happiness derives from the material world; spiritual happiness comes from being united with God. Children of this world have marriage for support and fulfilment; children of the next, live in the fullness of God's love. They need nothing else because God's love suffices them.
Fourth, from the Burning Bush experience, Moses implied that the patriarchs: Abraham, Isaac and Jacob although out of this world a long time ago, were not dead, but are now enjoying God's love in God's kingdom.
The mystery of afterlife is an open debate. Jesus himself arose from death and He alone has the authority to talk about it. Anyone who refuses to believe in Him; hits a brick wall. Winning or losing the debate is not important. What counts is to have God's gift. The resurrection is God's free gift given to those who have faith in Jesus. To honour the gift we don't do like children do. They love the gifts that please their eyes. A mature person unwraps the gift differently, that person sees something beyond the gift. The gift is the symbol of one's love for another person. It is the invisibility- the love of the giver- that counts, not the gift itself. We, Christians, receive God's free gift- eternal life- in the same manner. We take it with utmost care because we believe, that we don't deserve the gift, but God chooses to give it to us, and we respond to God's love with a thankful heart.