Brett Molina

USA TODAY

Apple CEO Tim Cook publicly confirmed he is gay in an opinion piece published Thursday, making him the highest-profile chief executive to come out.

In an essay published by Bloomberg Businessweek advocating for human rights and equality, Cook says he was inspired by Dr. Martin Luther King to set aside his desire for privacy to do something "more important."

"While I have never denied my sexuality, I haven't publicly acknowledged it either, until now," writes Cook. "So let me be clear: I'm proud to be gay, and I consider being gay among the greatest gifts God has given me."

Cook becomes the first openly gay CEO of a Fortune 500 company, according to gays rights group Human Rights Campaign, who applauded the Apple chief's essay.

"Tim Cook's announcement today will save countless lives," says HRC President Chad Griffin. "He has always been a role model, but today millions across the globe will draw inspiration from a different aspect of his life."

Cook says he's been open with others about being gay, but felt compelled to publicly come out to help others. "I don't consider myself an activist, but I realize how much I've benefited from the sacrifice of others," writes Cook. "So if hearing that the CEO of Apple is gay can help someone struggling to come to terms with who he or she is, or bring comfort to anyone who feels alone, or inspire people to insist on their equality, then it's worth the trade-off with my own privacy."

Reaction has been mostly positive. On Twitter, Apple's chief of global marketing, Philip Schiller, showed support for Cook. "Proud to work for you and be your friend," Schiller said.

Sarah Kate Ellis, president and CEO of GLAAD, applauded Cook and Apple's "long history" in demanding equality. "It is a game changer for corporate America," says Ellis. "He set the example for inclusion."

Public confirmations of sexuality have increased in Hollywood, and have started to appear in the sports world, including football player Michael Sam, who came out right before this year's NFL Draft. But it's rare to see in the business world, which makes the revelation by Cook -- head of one of the world's most profitable companies -- a much bigger deal.

"This serves as an opening of the door for other CEOs, senior-level managers, senior-level executives to say I'm ready to bring my authentic self to the office and I know now that it's not potentially a detriment, it's an asset to be out and proud in the workplace," says Justin Nelson, co-founder and president of the National Gay & Lesbian Chamber of Commerce.

Apple has been among the top American companies for embracing equality. Fred Sainz, vice president of communications at HRC, says Apple has achieved the top rating in their Corporate Equality Index every year since it was introduced in 2002.

But Sainz notes it will be important to watch how Cook addresses equality now that's he's publicly revealed his sexuality. "What we'll be interested to see is how he now uses his platform as the CEO of one of the world's most prominent companies to further advance equality and justice for people across the world."

Cook's piece published days after the Apple CEO criticized his home state of Alabama over gay rights. "We can't change the past, but we can learn from it, and we can create a different future," said Cook.

This is not the first time Cook's sexuality has been addressed. In June, CNBC hosted a segment on gay CEOs where one host seemed to out Cook as gay. "I think Tim Cook is fairly open about the fact that he is gay at the head of Apple, isn't he?" said Squawk on the Street co-host Simon Hobbs, causing an awkward silence. Hobbs quickly followed with "Oh dear, was that an error?"

Cook says the decision to reveal his sexuality was difficult, and hopes people focus more on his efforts running the tech giant. "I'm an engineer, an uncle, a nature lover, a fitness nut, a son of the South, a sports fanatic, and many other things. I hope that people will respect my desire to focus on the things I'm best suited for and the work that brings me joy."

The CEO also says he will continue to advocate for human rights and equality. "We pave the sunlit path toward justice together, brick by brick. This is my brick."

Follow Brett Molina on Twitter: @brettmolina23.