The Sadducees had laid a trap for Jesus. They did not believe in any resurrection of the dead.  For them, this life is all there is, but it was important to please God … even though they did not accept that they would give any account to God (Ecclesiastes 11:9; Romans 14:12). But Jesus has declared that He would rise again, and raise up all who believe in Him (John 6:39-40).  Plotting to ridicule Him,  and His confidence in the resurrection, they posed a riddle about a woman who had multiple marriages because each husband had died.  Their question was, "Whose wife will she be at the resurrection?" (Luke 20:27-33).  

Jesus did not answer the question.  Instead, He taught about the nature of marriage.  Jesus explained that marriage, sex and procreation are special gifts for our earthly life (Genesis 1:28).  However, in the great resurrection, those relationships will no longer be necessary or appropriate (2 Peter 3:13).  Instead of individual families multiplying to fill the earth, all those who are in Christ will be raised to populate the new heaven and new earth - where there will be no more birth or death and no need for marriage or sex.  The focus will be on God Himself, as is already the case for the angels.

Jesus did not dodge the question about the resurrection; He strongly affirmed that it will happen.  However, He removes the presumption that the 'life to come' will be exactly like this life (only nicer!).  The Bible does not give us full details of what that life will be like, because we don't need those instructions right now [the Bible reveals God's mind about those things we have to do, and not those things we would like to speculate about (Deuteronomy 29:29)].  But Jesus did make clear that, after the resurrection, life will be different; disconnected from our personal ambitions and pleasures, and totally focussed on Him in the security and joy of being His children.

This does not mean that marriage is unimportant in this world.  It is God's special gift to enabling people to live in committed personal security, learning love and service and the enjoyment of relationship.  Sex with its powerful emotional impulses needs to be constrained within marriage, so that family groups may develop securely.  Marriage is also a parable of the true relationship between Jesus Christ and His church (Ephesians 5:22-33).  But all the wonderful blessings of human relationship in marriage cannot compare to the overwhelming joy of experiencing the undiluted love, affirmation and relationship with Father God for all eternity.  So let those of us who are married treasure this gift, protect it and develop within it until we are called to Glory.  For those who are unmarried, remember that marriage is not your salvation - Jesus is: and at the resurrection all of our attention will be on our wonderful Lord.  Living in the light of that reality should help us to understand the priority of worship as we fix our eyes on Jesus (Hebrews 12:1-2) whether we are married or not.