While other companies are avoiding endorsing Colin Kaepernick, Nike has embraced him after he was unveiled as the face of an ad campaign for the 30th anniversary of their "Just Do It" slogan on Monday. The ad's message reads: "Believe in something. Even if it means sacrificing everything."

Kaepernick played six years for the San Francisco 49ers before opting out of his deal in 2017, following backlash for kneeling during the national anthem in 2016 preseason games as a protest against racial inequality and violence.

He has since become a polarizing figure in the United States, especially with President Donald Trump attacking him and others who have followed his lead for "disrespecting" the national anthem.

No NFL team has signed him since either, with Kaepernick currently suing owners for colluding to keep him out of the league. Last week, arbitrator Stephen Burbank notably denied the NFL's request to dismiss the case, which could lead to a trial as Kaepernick seemingly has enough evidence.

And with Nike's new ad campaign, coming just days before the start of the 2018 NFL season, it is bound to stir national debate once again.

According to ESPN's Darren Rovell, Nike continued to endorse the 30-year-old as they have done so since 2011, though they did not feature him in any campaigns since 2016 until now.

Colin Kaepernick Colin Kaepernick's protests against racial inequality and violence have seen him not get signed by any NFL team since leaving the San Francisco 49ers. In this picture, Kaepernick receives the SI Muhammad Ali Legacy Award during SPORTS ILLUSTRATED 2017 Sportsperson of the Year Show at Barclays Center in New York City, December 5, 2017. Photo: Slaven Vlasic/Getty Images for Sports Illustrated

Many have praised Nike for their bold but risky move in sticking by Kaepernick, especially as other companies such as Adidas claimed they would have only signed him if he joined an NFL team.

However, others have threatened to stop wearing and buying Nike merchandise, while some on social media have even posted videos of themselves burning Nike gear.

"We believe Colin is one of the most inspirational athletes of this generation, who has leveraged the power of sport to help move the world forward," Nike's vice president of brand for North America Gino Fisanotti told ESPN. "We wanted to energize its meaning and introduce 'Just Do It' to a new generation of athletes."

The likes of Serena Williams, LeBron James, Odell Beckham Jr., Shaquem Griffin and Lacey Baker are also part of the campaign. Williams was one of many athletes who responded to the news of Kaepernick and the ad campaign on social media.

The NFL notably announced a new policy in May that would penalize teams and players for protesting on the field during the national anthem. They could, however, remain in the locker room during the anthem.

However, the policy was put on hold in July when the players' union filed a grievance as the NFL and NFL Players Association look to reach a resolution. And so, protests continued on the first day of 2018 preseason with Kaepernick showing his support.