"Consussion" seems like a strange Christmas release: Hey, lets go see that movie where pro football players with brain damage kill themselves.

And in truth, it's not a knee-slappin' good time at the theater.

But it is more appropriate to the season than you might guess - the story of a deeply religious man who undertakes a moral crusade, motivated by an abiding faith that gives him the courage to take on the NFL, based on his conviction that "God does not want us to play football." He was not born in this country, so he does not understand that God and football in this culture are used interchangeably.

The man is Bennet Omalu (Will Smith), a Nigerian immigrant and devout Christian working as a county pathologist in Pittsburgh when he is assigned the corpse of pro football Hall of Famer Mike Webster (played in flashback by David Morse).

Webster is dead at just 50, following an apparent breakdown - he spent his last months living in a pick-up, erratic and delusional and suffering, jabbing himself with a Taser just to be able to fall asleep. On the autopsy table, Omalu pulls from the deceased a set of loosely fitting false teeth - Webster was keeping his bridgework in place with super-glue. These details are actually true.

Omalu, as is his habit with the dead, addresses Webster as if he were still alive, asking him to help disclose the cause of death, as if addressing a tormented spirit (Webster appears from time to time as an apparition).

Omalu suspects a brain abnormality, and, finding none at at first, uses his own money (the county balks at the expense) to fund additional tests that will provide comprehensive and detailed picture of Webster's brain.

What he finds is stunning: Toxic proteins have accumulated in Webster's brain, clogging the pathways that permit normal function, a condition that Omalu suspects is related to head trauma brought on by the player's violent profession.

What follows is a classic outsider saga and man-against-the-system muckraker - the National Football League attacks Omalu's reputation, he studies more dead players and finds more damning evidence. He gets help from his wisecracking boss (Albert Brooks, very good), a guilt-ridden team physician (Alec Baldwin) and in his spare time falls in love (with Gugu Mbatha-Raw),

As drama, "Concussion" is sometimes moving and provocative, sometimes clunky and melodramatic. Writer-director Peter Landesman has a weakness for pointedly stirring speeches, and a few scenes trip over themselves.

But there is something gutsy and affecting about the movie. It's not just challenging the NFL (which it deflates by casting "Idiocracy" star Luke Wilson as Roger Goodell). It's challenging you, me, everybody who wants to watch football like we did 20 years ago, before we knew the game killed people who suffered repeated blows to the head (cited players include former Eagle Andre Waters).

The kind of hits that have been commemorated for decades on artsy slow-motion film, set to waltz music for our amusement, and moved commentators to celebrate twitching, unconscious men who got "jacked up."

"Concussion" settles the science of Chronic Traumatic Encephalopathy, but its real questions are moral.

What if Omalu is right - about God, that is.

As Omalu's boss jokes in the movie, the NFL is so powerful it owns a day of the week.

A day that used to belong to Someone Else.