JM: For any one who studies ancient Mediterranean societies this is a amusing observation.
I really don't think that what Marvin says is true when taken literally.
For one, sports has always been a kind of practical way to rehearse either individual "aristocratic" prowess in war, or "hometown" rivalry in preparation for war. Rallying around the "banner" of the team or the colors of the club, or becoming a fan of an individual, was a way to assert a form of "patriotism" ( a word that is a bit anachronistic in certain contexts.)
Further, it is not at all clear when "sports" became separate from "religion," just like it is not at all clear when literature and drama became separate from "religion." The problem is more our modern concept of religion. Religion for the ancient Greeks was not about morality or theology, but more about bargaining with the gods, protecting the home, and the polis, making a way through life's stages, and locating the family's or the city's relation in the order of the things. What we today call "sports" (organized competition with set rules) was another part of this relation to the cosmos, to the family and to the city. Part of what is truly despicable (or at least strange) about modern Judaism, Christianity and Islam, is that it creates separate categories for such civic functions as sports or drama -- allowing them to be valued or condemned for their supposed "moral" features -- for their promotion of or their harm to "morality." Let me add that this way at looking at sports and drama was not exclusive to the modern religions "of the book" but was also Plato's way of evaluating sport and art in some of his more "pure" moments.
If anyone is interested in a good overview of some of these themes in relation to Ancient GreeceM I would recommend _Sport and Society in Ancient Greece_ by Mark Golden.
One thing I am sure of is that neither sport nor religion can function in our complex-highly populated mass society, in the same way it did in ancient Greece. But I am not sure that it is correct to say that sports in our society is an "opiate." In some small respects sports does seem to "function" in the same way as it did in Ancient Greece, as a preparation for war. The Superbowl especially at times takes on aspects of what Alex Cockburn, once called "an electronic Nuremberg rally."
Jerry