Worshipping God must be on His terms.  Without revelation, nobody can understand God's character, or what pleases Him (Ephesians 5:10).  The best they can do is to see the awesome creation and conclude the Creator will demand an account of our time spent here (Romans 1:20).  Jesus wanted to discuss the resurrection: a tutorial for the disciples who would soon witness it, and a theology lecture to the Sadducees who thought it could not happen.

Jesus always placed His teaching in the context of what His hearers already knew: either the world around them (hence many agricultural or financial parables), or the Old Testament Scriptures – attributing His authority to Father God and His written Word.  Why had the Sadducees ignored the scriptures?  Because they did not fit into the false theology they had constructed.  In other words, they had invented a wrong teaching which left no room for God's truth.  When Jesus said, "You are badly mistaken", the original word meant 'deceived', 'deluded', 'seduced' or 'wandered away' from the truth.  Every false theology is a seductive deception to deluded people to wander away from what is right.  That is why it is essential to have God's Word as our authority, or else we will be prey for false teachers and our hearts will wander (2 Timothy 4:3-4).    

Because God is not confined by time, there is no past or future to Him - He sees both with equal immediacy, as if everything was happening now.  The souls of the dead are also well known to Him, and He remains their God.  The title which God uses for Himself, "I AM" (in Exodus 3:14), does not just mean that He is present in every age, but that every age is the present for Him.  Not only is that true about the time span of human history, but also about the whole of eternity.  That is why God is still the God of those who died in faith (Hebrews 11:39-40).  So, God's statement to Moses, about His continuing relationship with the patriarchs, was Scriptural proof of the after-life.

Although heaven and hell are rarer topics for Gospel conversation these days, they are crucial to explain the eternal nature of God, and the consciousness of life for those who have died (Luke 12:16-21).   As with any journey, our direction will determine our destiny: but the wise know that it is best for our destination to shape our direction.  It is the greatest mistake to live with no thought of eternity; and a most selfish negligence, if Christians stay mute about eternity (Luke 16:19-31).