In Jesus’ day, the religious leaders were in two main groupings: Pharisees (who believed in an afterlife with a bodily resurrection), and the Sadducees (who did not). Jesus had been saying that He would rise from the dead (Matthew 16:21, 17:9, 17:23, 20:19), and therefore threatened the theology and credibility of the Sadducees in the eyes of the people. Those leaders wanted to discredit Jesus and so invented a story in the form of a riddle to trap Jesus and prove that they were right.
 
In the Old Testament, if a man died without having children, his brother had the responsibility to marry the widow and give her children who would run the brother's estate (known as levirate marriage – Deuteronomy 25:5-6). So the Sadducees made up a scenario in which seven brothers married a widow, asking whose wife she would be at the resurrection. They assumed that Jesus would not be able to answer this riddle.
 
It was an elaborate story, but it did not faze Jesus. He told them that they did not know what they were talking about because the Scriptures make clear that marriage is only for this life: heaven does not need sex for procreation, comfort or enjoyment. All the attention will be on the Lord, and we will be fully satisfied in serving and worshipping Him, as the angels are now.
 
The resurrection is still very important in spreading the gospel. The resurrection of Jesus showed that death had been defeated and sin had been fully atoned for. It also pointed the way to the resurrection of every believer (1 Corinthians 15:20-23). Indeed the whole of creation will be transformed when the church is raised with new bodies (Romans 8:19). Yes, some clever people like to argue against the possibility of resurrection: but Jesus was raised and seen by so many eye witnesses. He also solemnly promised to raise all those who believe in Him (John 6:39), and His example secures our confidence. Of course, those who do not want to be judged by Jesus might like to think that there is no afterlife at all: but they are wrong. So spread the good news that those who believe in Jesus will meet Him and be with Him for ever!