This movie demonstrates the absolute futility of seeking wealth, notoriety, women, power, and earthly treasures. Kane seeks after all these things and ends up a lonely, depressed man with no friends to speak of. At the very end, Kane has a moment of awakening when he realizes the purest and happiest moments of his life was when he was a child living with child-like faith. As a child, he cared not for wealth, notoriety, women, power, or earthly goods. It reminds Mark 10:15, "Truly I tell you, anyone who will not receive the kingdom of God like a little child will never enter it."
Whether Kane had a true repentance experience is unknown, the movie implies that this is left between him and God. What I find puzzling, however, is William Hearst's outright hatred for the film, wanting to see it completely destroyed. The movie is loosely based on his life. To me, the ending shows Kane's yearning for something virtuous and meaningful. Yet, Hearst wanted vindication of Kane's life in which he pursued wealth and power. Surely, Hearst's life is not identical to Kane's, but it is safe to say he pursued much of the power and wealth depicted in the movie. I guess it only back up that power and money does truly corrupt a man.