Alexander, an aging atheist actor/psychologist/writer with a younger actress wife, a teenage daughter, and a young son (who is referred to as "Little Man") experiences the opening throes of the end of the world by a nuclear holocaust. In despair the protagonist vows to God to sacrifice all he loves ("I'll give Thee all I have, I'll give up my family, whom I love, I'll destroy my home and give up Little Man") if only this good act of fate may be undone, and to this end he sleeps with a local woman whom he believes to be a witch.
When he wakes up the next morning everything seems "normal", but whether Alexander dreamt the whole episode is never made explicit. Nevertheless, Alexander sets forth to give up all he loves and possesses, burning his house and being driven off to an institution.
More Here. http://en.wikipedia.org/wiki/The_Sacrifice