SAN FRANCISCO -- Early this year, Colin Kaepernick spent 16 hours over two days on a tattoo artist's table, turning his back into a mural. He already had a psalm inked on each bicep and the phrase "Against All Odds'' in looping script across his upper chest. The new one looks like a fresco from an Italian cathedral.

"It's angels fighting demons,'' Kaepernick explained Monday night after his audacious debut as an NFL starting quarterback. "For me, it's life. Always trying to make the right decisions. It's always a fight to try to do the right thing.''

His performance in the 49ers' 32-7 win over the Bears set up just such a conflict. Kaepernick stole Monday Night Football, and he may have swiped Alex Smith's job in the process. Jim Harbaugh could have tried to quash the incipient quarterback debate by saying he couldn't begin to determine next week's starter until he knew whether Smith's concussion symptoms would persist. He did not do that.

"We'll see,'' the coach said. "I usually tend to go with the guy who's got the hot hand, and we've got two quarterbacks that have got a hot hand.''

The debate itself represents a side of another battle. Kaepernick's bravura night on the national stage deserved wild ovations, gasps of wonder, maybe even roses thrown from the upper deck. Is it impossible, just for a day, to savor that all on its own?

He's a fascinating 25-year-old, possibly the transformative quarterback that many fans believe Tim Tebow to be. He is both deeply and blithely religious. His Twitter feed overflows with determination and enough sweetness to decay molars. The tattooed psalms speak of strength in the face of an enemy. "Though an army besiege me, my heart will not fear.''

Kaepernick grew up in Turlock, a small town in the agricultural center of California, about two hours from San Francisco. He was adopted, a biracial child who completed an otherwise white family. His parents had two biological children, but they had also lost two baby boys shortly after birth.

When Kaepernick was in high school, MLB scouts salivated over his fastball, which reached 94 mph. He is built like a classic pitcher, long and lean, and he was even leaner as a teenager. But he yearned for big-time college football. The feeling was not mutual.  

He ended up at the University of Nevada in Reno, in the Pistol offense, throwing for 2,000 yards and rushing for 1,000 three seasons in a row. He was an "A" student, recruited by some of the Ivies. He sounds like a gentle geek when he talks in public. His demeanor makes a mockery of Carolina owner Jerry Richardson's insistence that body ink signals poor character and that he wanted none of it on quarterback Cam Newton, the Panthers' prize in the 2011 draft.

Kaepernick was the 49ers' hidden gem. He went 35 places below Newton in the draft, fourth in the second round, sixth among quarterbacks chosen that year. He expected, or at least hoped for, better. The "Against All Odds'' tattoo explained everything.

Watching him succeed in the NFL, seeing if those coltish legs can hold up against the mayhem, would be thrilling. But he needs a job for that to happen. At some point, he will need a debate to lean toward him, and away from an incumbent.

The debate isn't pretty, but it's not necessarily a demon, either. It's only right to weigh whether Harbaugh should violate the football code, which says that players do not lose jobs because of injury. In 2012, a concussion leading to an ouster seems especially disturbing. However slightly, it would counteract efforts to persuade players to report brain-trauma symptoms.

But if the code always held up, Tom Brady wouldn't have finished out the 2001 season for the Patriots. Drew Bledsoe would have reclaimed his position, and who knows what would have been lost? One Super Bowl? All three titles? All five appearances? Giselle? The hoodie?

Kevin Kolb lost his job because of a concussion and Michael Vick's surprising rebirth as a quarterback in 2010. Kolb's work in Arizona suggests that he might have ultimately forfeited the gig on merit alone, but the Eagles couldn't have known that at the time. They did, after all, choose him as the starter that season, and his concussion came in the second quarter of their opener.

The Kolb experience also serves as a caveat against becoming smitten with a quarterback after a limited sample of his work. Kaepernick's tantalizing Monday night doesn't obscure Smith's 70 percent completion rate, the highest in the NFL, or the fact that any quarterback might have thrived behind the 49ers' protection the last few weeks. It also doesn't negate Smith's fourth-quarter playoff slaying of the Saints, next up on the 49ers' schedule.

But those deep passes from Kaepernick, the kind that Smith almost never attempts, will be hard to overlook. He came out slinging the ball, fearlessly, and the Bears didn't make him stop. Only the demands of the scoreboard and time management did.

He ended up with 243 yards passing on 16-of-23 accuracy and two touchdowns against reputedly one of the best defenses in the NFL. Kaepernick had collected 231 yards of his total less than four minutes into the third quarter, when the 49ers took a 27-0 lead. Smith has surpassed 243 yards only once this year. Smith's longest pass for the season is 55. Kaepernick's longest in his debut traveled 57 yards.

Late in the game, after tight end Vernon Davis caught an 11-yard pass in tight coverage, he went back toward Kaepernick, pressed his hands together and bowed.

"I was just so proud of him at that moment because that ball he threw me, it was one of those balls that you see Tom Brady throw,'' Davis said. "Second window, right on the money. I didn't expect the ball to come because we've ran that play quote a few times and the tight end doesn't usually get the ball on that play. But he saw it, and he just put it there.''

Lest it appear that Davis was sending a sideways insult in Smith's direction, bear in mind that he backed Smith through all the years he floundered and exalted as the No. 1 draft pick of 2005 shucked the bust label last year. "I can't choose sides,'' Davis said. "I am here to support either one of them.''

For a quarterback's teammates, the first round of the debate, conducted in the locker room, is almost always a demon. After a game like Monday night's, crushing another elite team on national TV, they want to relish the moment, not delve into the politics of quarterbacking.

Kyle Williams, the recipient of that 57-yard pass, rhapsodized about Kaepernick's accuracy and talked about the hints of a pitcher he can detect in that arm. The son of White Sox general manager Kenny Williams, Kyle knew that Kaepernick had been drafted by the Cubs. They took him in the 43rd round three years ago, even though he hadn't thrown a baseball since 2006. Williams also played baseball, and he has imagined face-offs with Kaepernick. Williams usually gets a hit in those fantasies.

"We do talk a lot of baseball, but that's normally where the conversation stops,'' Kaepernick said, " 'cause we have a very large disagreement when we talk about if he could hit me or not.''

So for a few seconds, he did talking about besting a teammate, albeit in an alternate universe. On the field, he had made an extraordinary case for himself. He didn't make an argument against Smith. That task belongs to others. He has to settle for a glorious debut, and owning Monday night.