What does Luke 20:31 mean?

Jesus is teaching in the court around the temple. Local religious leaders, jealous and fearful of His popularity, are trying to discredit Him using religious, legal, and theological paradoxes. So far, they've not only failed, but they've humiliated themselves (Luke 20:1–26).

Now comes the Sadducees' turn. They don't believe in the resurrection of the dead, but they know Jesus does. They value the Mosaic law, which includes the practice of levirate marriage. If a married man died before his wife could conceive an heir, his line would die and he would be dishonored. The cultural answer, which God incorporated into the Law as "levirate marriage," was for the deceased man's brother to marry the widow; their first son would be the original husband's heir (Deuteronomy 25:5–6).

The Sadducees combine the two concepts: a woman marries, but her husband dies with no heir. She marries his next-oldest brother, but he dies with no heir. This continues through seven brothers. Then, she dies. If the resurrection is true, which brother is she married to? All of them? Just one? This is not really a question as much as a claim: that the concept of resurrection is ridiculous (Luke 20:27–33).

In Jesus' era, interactions like this were common. Rabbis and students would ponder thought experiments, attempting to better understand and apply Scripture. The problem here isn't the question itself, but the motive in which it's asked. The goal is not enlightenment. It's to prove Jesus is not worth following.

Of course, Jesus was and is exactly who He claimed to be. He is worth following. And fallible humans can't trap the Son of God in a false paradox.