From: Mark 12:18-27
The Resurrection of the Dead
 And Sadducees came to Him (Jesus), who say that there is no resurrection; and they asked Him a question, saying  "Teacher, Moses wrote for us that if a man's brother dies and leaves a wife, but leaves no child, the man must take the wife, and raise up children for his brother.  There were seven brothers; the first took a wife, and when he died left no children;  and the second took her, and died, leaving no children; and the third likewise;  and the seven left no children. Last of all the woman also died.  In the resurrection whose wife will she be? For the seven had her as wife."
 Jesus said to them, "Is not this why you are wrong, that you know neither the Scriptures nor the power of God?  For when they rise from the dead, they neither marry nor are given in marriage, but are like angels in Heaven.  And as for being raised, have you not read in the book of Moses, in the passage about the bush, how God said to him, `I am the God of Abraham, and the God of Isaac, and the God of Jacob'?  He is not God of the dead, but of the living; you are quite wrong."
18-27. Before answering the difficulty proposed by the Sadducees, Jesus wants to identify the source of the problem--man's tendency to confine the greatness of God inside a human framework through excessive reliance on reason, not giving due weight to divine Revelation and the power of God. A person can have difficulty with the truths of faith; this is not surprising, for these truths are above human reason. But it is ridiculous to try to find contradictions in the revealed word of God; this only leads away from any solution of difficulty and may make it impossible to find one's way back to God. We need to approach Sacred Scripture, and, in general, the things of God, with the humility which faith demands. In the passage about the burning bush, which Jesus quotes to the Sadducees, God says this to Moses: "Put off your shoes from your feet, for the place on which you stand is holy ground" (Exodus 3:5).
Source: "The Navarre Bible: Text and Commentaries". Biblical text taken from the Revised Standard Version and New Vulgate. Commentaries made by members of the Faculty of Theology of the University of Navarre, Spain. Published by Four Courts Press, Kill Lane, Blackrock, Co. Dublin, Ireland. Reprinted with permission from Four Courts Press and Scepter Publishers, the U.S. publisher.