Ok, this was a 1950's "COMMIES ARE EEEEVIL!!!" movie, black and white.
Main plot was that a student, I think he was a military cadet, get hoodwinked by the EEEVIL commies into becoming a commie. Later he realizes how EEEVIL the commies are, after some confrontation with his father, and is killed in a carwreck fighting his former comrades. He dies near his father, who he dies to save, I think.
At the end, a tape he'd made is played to his graduating military cadet class in where he denounces communism and himself and implores his classmates to fight communism until it's wiped out, because, of course, commies are EEEVIL and want to create a world where no toher system exists, unlike americans, who want to create a world where only....uh. never mind.
Anyway, the actor playing the lead role was killed before filming was completed, but he'd done the end speech already so they redid the ending to have his character die, and then play his recorded confession, in a sickeningly melodramatic way involving a light, seemingly to come down from heaven, shine on the podium as his recording played.