It questions the ethics of imposing radical beliefs on children, especially when those beliefs hinder their ability to function in society.

The family's journey to honor Leslie's final wishes (a Buddhist cremation) leads to a confrontation with her traditional Christian father, Jack (played by Frank Langella). Production and Reception Captain Fantastic (2016) - IMDb

The film explores the "middle ground" between extreme intellectualism/isolation and the consumer-driven outside world.