Kluwe, who was photographed for the magazine shirtless and wearing a pair of jeans, has said he is not gay, but is using the photo shoot as a way to show his support for people who he believes are not treated equally by the law.
In recent weeks, he has taken to Twitter, written an open letter on Deadspin and even challenged Minnesota politicians to a debate on the issue.
"It's all about the Golden Rule," he told Out. "Treat other people as you want to be treated. It's that simple. It’s something that needs to be spoken about, and it's something I can do while fulfilling my job as a football player."
The Minnesota Same-Sex Marriage Amendment will be featured on the state's November ballot. If passed, the measure would define marriage as between one man and one woman in the state of Minnesota.