Since most of the political bellyaching about this movie seems to be coming from the self-righteous right, I'm going to ignore it and just talk about the film itself. What starts out as a well-acted exploration of family tensions - especially those between a relatively uneducated set of middle-class parents and their college-educated son - gives way to the clumsy, overwrought melodramatics of the second half of the film. The death of Robert Walker during filming doesn't really excuse or explain the awfulness of the last hour. There's an early scene between John and his mother in which he explains that his goals are the same as those of the Catholic Church in which they were both raised but that his methods are different. The fact that he is a Communist (McCarey and some of his apologists seem to suggest) means that those goals must be evil because the methods are evil. Just stop thinking for yourself; trust in God and the FBI. It's a dangerous message, and not all that far off from the one that the Communists drilled into their victims (for "God and the FBI" substitute "the Party"). Oh, well . . . I guess I couldn't avoid the political bellyaching.
The sad thing is that the lead actors are all so good. McCarey was brilliant at getting excellent naturalistic performances from his actors, and Helen Hayes, Robert Walker, Van Heflin and Dean Jagger are all extremely convincing until the film collapses into right-wing agitprop at the halfway mark. Even Hayes couldn't do much (except overact) with her climactic scene in which her character tries to use a football analogy to get her son to see the light.