The Sadducees had their own idea about how life should work … they thought that 'what you see is all there is and when you are dead you are gone for ever'.  They concocted a scenario for Jesus to comment on regarding Levirate marriage – a Mosaic law to ensure that a dead man's property remained in the family (Deuteronomy 25:5-10).  They asked that if a woman had many husbands, whose husband would be in heaven?  They thought it was a clever way to logically prove that there was no heaven or hell (Mark 12:18-23).  

But without accepting God's view, they were bound to get it wrong.  The problem of not starting with God, is that you cannot arrive at God.  And there is certainly no way we can know about the after-life, if we ignore the Scriptures and ignore Jesus who came from heaven (John 3:31).  When we reduce God to our earthly level, we automatically reject His power, and His role as the primary factor in our origin, existence and destiny (Genesis 1:26-27).

The Sadducees, who did not believe in an after-life or angels, got Jesus' rebuke. "You are in error", really means, 'you are self-deceived'.  They ignored God's Word and made up their own universe - they were fooling themselves (as does everybody who navigates without the Scriptural compass).  Marriage, Jesus said, was for earth and not for heaven.  We need marriage as a framework for sex and society - but the angels already live by a different social order.  Their joy and satisfaction is in the adoration and service of the King of heaven.  One day, our resurrection bodies will meet the needs of a Jesus focussed society, in which we are all children of one Father.

While God hates divorce (Malachi 2:16), and Jesus spoke far more clearly than Western culture about remarriage during the lifetime of a divorced spouse (Matthew 19:3-9), widows and widowers are quite free to marry again.  But the thrust of Jesus' comment was not so much to define marriage or heaven, as to alert them to the folly of self-deception of using this life for self through a wilful disregard of God's Word.  It is a huge challenge to any Christless society, and for the individuals who do honour Jesus.  The key question is whether they have the humility to accept God's Word about the future and choose to change to fit in with God instead of demanding that He must fit in with us.