If a person has a lack of knowledge, in reference to the word of God, they will ask some foolish questions. Well, in Luke 20:27-36, the Sadducees asked Jesus a ridiculous question, because they did not believe in the afterlife.
In life, we will encounter some people that do not believe in Heaven or Hell. But that does not negate the fact they both exist.
For more understanding read the book of Revelations.