Who is Beth and Christopher Dick from Valis and what is their importance?

Beth is Horselover Fat's wife and Christopher is their five-year-old son, whose life is threatened by an undiagnosed and potentially fatal inguinal hernia until God through a blinding flash of pink laser light discloses the defect to Fat in time for successful surgery. Christopher stops being a troublesome child. In 1976, Beth leaves Fat, taking beloved Christopher away, intending to return after Fat kills himself. This triggers Fat's second suicide attempt, which ought to have succeeded but miraculously does not. She never believes Fat's philosophy. She accosts him for being able to do nothing right. Beth is Fat's second wife (first unnamed) and both constantly demand support payments. When Fat for a period disappears, Philip K. Dick admits that Fat had only been a mental projection. He explicitly calls Christopher his son and takes over payments. He recalls in 1974 secretly administering to Christopher his own version of the sacraments of baptism, confirmation, and communion.