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The Colorado Buffaloes haven't been relevant in college football for over a decade, but fans can enjoy happier times during the upcoming 30 for 30 documentary The Gospel According to Mac, which airs Wednesday night at 9 p.m. ET on ESPN.

The focus of director Jim Podhoretz is Bill McCartney, the most successful coach in Colorado history. In 13 years under McCartney, the Buffaloes won 93 games and captured their only national title, which came in the 1990 season. Kordell Stewart, Michael Westbrook, Eric Bieniemy, Alfred Williams and Jay Leeuwenburg are among his former players who went on to NFL careers.

Listening to how McCartney transformed Colorado from an also-ran into a national powerhouse for a short time will be compelling on its own. This clip offers a brief glimpse into how McCartney's charisma and determination worked wonders on the recruiting trail, per ESPN Films 30 for 30:

Of course, Colorado's on-field success will only be part of the story.

A February 1989 article by Rick Reilly for Sports Illustrated documented the number of legal issues plaguing the Buffaloes in the late 1980s, which Reilly went so far as to call a "crime wave." By his count, more than 24 of McCartney's players were arrested between 1986 and early 1989 alone.

But in the article, Theo Gregory, then an academic coordinator for the Colorado athletic department, discussed some of the socioeconomic and racial factors at play in Boulder, Colorado—factors that still resonate today across the country:

If you're a black football player here, you're ethnically a minority because you're black, socially a minority because you're an athlete, culturally a minority because you might come from the projects, economically a minority because you can't afford to drive a BMW and physically a minority because you're bigger than everybody else. Somebody racially slurs you, and you might have a tendency to overreact.

Colorado wasn't the first, nor will it be the last to bend NCAA rules and/or see its players break the law en route to glory on the field. In fact, that aspect of the documentary won't be altogether dissimilar from previous 30 for 30 documentaries Pony Excess and The U, which focused on SMU and Miami's football programs, respectively.

What will set The Gospel According to Mac apart from other 30 for 30 entries is the focus on McCartney's personal and family life.

In 1988, McCartney's daughter became pregnant by Sal Aunese, who was then the Buffaloes' starting quarterback. Kristy McCartney gave birth to the child in April 1989, five months before Aunese died of stomach cancer.

Near the end of his coaching career and in retirement, McCartney's involvement with Operation Rescue and the Promise Keepers has also become extremely polarizing. Operation Rescue is a staunch anti-abortion Christian organization, while the Promise Keepers, founded by McCartney in 1990, looks to "ignite and unite men to become warriors who will change their world," according to its website.

Johnette Howard also recounted in an October 1994 piece for the Washington Post the extent to which McCartney proselytized an anti-gay lifestyle:

McCartney irks non-Christians by speaking of restoring America to Jesus. He's spoken to Operation Rescue members and other anti-abortion groups. He's called gays "stark raving mad" and undeserving of the same legal rights as "people who reproduce." At a 1992 news conference he conducted at a university lectern while wearing a Colorado emblem on his shirt, he also called gays "an abomination against Almighty God" and confirmed he'd joined Colorado for Family Values, a group that supported Amendment 2, the so-called "anti-gay rights" measure recently struck down by the Colorado supreme court.

In December 1992, Adam Teicher described in the Kansas City Star (via the Chicago Tribune) that handbills made the rounds on the Colorado campus depicting McCartney and Adolf Hitler side by side, such was the anger toward the coach:

The depth of hostility toward McCartney has little to do with football. The coach, a devout evangelical Christian, has been charged by critics with using the power of his position to further his beliefs and whip up an atmosphere of religious intolerance. [...] University President Judith Albino has received about 2,000 phone calls by office tally and about 600 letters on McCartney, more than on any other subject. They have been split between canonizing him and firing him.

In December 2014, Michael Weinreb caught up with McCartney for an article on Grantland. According to Weinreb, McCartney had toned down his role in the Promise Keepers. However, he maintained his stances regarding marriage and homosexuality.

Whether you agree with McCartney's views or not, rarely do you see a head coach at a major college so publicly committed to his religious beliefs. Imagine seeing one of today's top coaches compared to Hitler as a result of his devotion to a certain cause.

McCartney is undoubtedly a controversial figure, making The Gospel According to Mac a highly anticipated addition to the 30 for 30 series.