Here’s what I’ve got:
It owns a day of the week, which church used to do for more people.
It’s the closest thing we have to “gladiators” or “warriors” in the modern age.
Regional tribalism.
Gambling.
Fantasy football. (Which is one of the primary, if only, ways that guys retain long-term friendships across distance and children.)
We like violence more than we admit.
A lot of guys (and some gals) like to sit in relatively dank bars, drink beer, and eat crappy fried food for a portion of Sunday to put off the reality of an upcoming workday, so it clicks there too.
You played the sport and like “couch-quarterbacking” it from the bar stool (or your couch).
Food.
Chances to get together.
We like to see new beer commercials and insurance commercials with celebrities in them.
It’s a way to stay connected to friends across distance (i.e. fantasy but also shit-talk texting).
We see the hypocrisy in suspensions relative to violations, and it secretly comforts us because of the hypocrisy in our own lives every single day that we gloss over :)
The players become characters (“I’m a football player for six days. On Sundays I’m an entertainer.” — Chad Johnson)
We like to debate merits.
We like to think we know more than professionals in every conceivable cranny of life, and especially guys who make millions of dollars to play what’s at heart just a game.
What else would you add?
Beer and the NFL are the modern American version of "bread and circuses."
Football as religion is actually quite compatible with Christianity (maybe other religions as well) because anyone who’s witnessed a player thanking God for a touchdown knows that God is a big fan. But God has both a sense of humor and of suspense regarding His involvement with the game. You see, almost all those touchdowns God grants willy-nilly are feints, head fakes if you will. You don’t get to know which team’s touchdowns are REALLY blessed until as late as 1 second left in the fourth quarter of the Super Bowl, depending on how whimsical God’s feeling that day. It’s good that God has a pleasant hobby to relieve the stress of all the wars, disasters, birth defects, cancers and pandemics, etc., that plague his fans, but which are not so easy to tackle as a simple touchdown. Thank God for football. At least SOMEBODY wins!