The question of the one bride and the seven brothers is not a question in search for the truth. The Sadducees do not expect, indeed, do not want, an answer. They hope to stump Jesus, and thus to demonstrate how “foolish” ideas of a resurrection from the dead are. The purpose of this question is not, as some of their earlier questions had been, to “get Jesus into trouble,” but to further the dogma of this group, that there is no resurrection after death. If Jesus, the most noted and unstumpable teacher alive, could be stumped by their question, then He would become (reluctantly) an endorsement for their view.
How often do I confuse what I think with what God thinks?