"Some Sadducees (who say that there is no resurrection) came to Jesus, and began questioning Him, saying, “Teacher, Moses wrote for us that if a man’s brother dies and leaves behind a wife and leaves no child, his brother should marry the wife and raise up children to his brother. “There were seven brothers; and the first took a wife, and died leaving no children. “The second one married her, and died leaving behind no children; and the third likewise; and so all seven left no children. Last of all the woman died also. “In the resurrection, when they rise again, which one’s wife will she be? For all seven had married her.” Jesus said to them, “Is this not the reason you are mistaken, that you do not understand the Scriptures or 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." (Mark 12:18-25)
The question posed by the Sadducees reflected the Jewish custom of passing childless married women whose husbands were deceased on to younger brothers in the same family. Christ answered their faulty premise, pointing out that there will be no marriages taking place in heaven. Humans will become immortal like the angels. There will be no need to produce offspring. See also the parallel text of Luke 20:34-36.
What takes place in the heavenly realm is quite unlike our experiences on earth. Jesus Christ continues His reprimanding of the Sadducees with the following remarks:
"But regarding the fact that the dead rise again, have you not read in the book of Moses, in the passage about the burning bush, how God spoke to him, saying, ‘I am the God of Abraham, and the God of Isaac, and the God of Jacob’? “He is not the God of the dead, but of the living; you are greatly mistaken.” (Mark 12:26-27)
God will give us much more fulfilling things in heaven than any temporary pleasures available to us in this life. He does value the institution of marriage, but it will not exist in heaven. The same is true of family units. We are all included into the family of God by faith. We are united through the Person and work of Jesus Christ.
The Mormon concept of celestial marriage expressly contradicts the teaching of Christ. In addition, wives who lost their husbands in this life and chose to remarry would be guilty of committing adultery because according to Latter Day Saint theology they would be forever bound to their first spouse.