Tim Cook coming out is a big deal

It's a big deal. It shouldn't be. I hope that within a few more years it won't be. But in today's world, Tim Cook's acknowledgment that he is gay is a deal of Bidenesque proportions.

Of course by now millions of Americans have stopped hiding our sexual orientation from others and this is the single biggest reason that bigotry has declined. The reality of who we are has steadily undermined the prejudice against us. But the fight is far from over, and the incompleteness of the process of our being honest about ourselves is part of the reason for that.

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It is a very good thing that people have learned that their relatives, friends, students, customers, teammates and others with whom they deal regularly include people who are gay, lesbian, bisexual or transgender.

It adds to the momentum against prejudice when prominent, highly respected personalities acknowledge their membership in a group about which negative, inaccurate stereotypes still exist. The number of celebrities in the entertainment and literary fields who have done this has reached critical mass, and openly gay or lesbian elected officials are no longer rarities.

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But, to be honest, none of these groups commands the respect from some segments of American opinion that are needed to make up a strong national consensus. Conservatives, i.e. those likeliest to have some lingering discomfort with the notion of complete acceptance of gays and lesbians by society, listen to lesbian and gay singers, laugh at their jokes, read their books, and know that there are LGBT politicians (although none that they vote for) but these are not the leaders they most respect, nor the people they hope their children will grow up to emulate.

That is why it was so helpful in our effort when Michael Sam and Jason Collins affirmed that being gay in no way meant they couldn't be very skillful at physically demanding sports. And it is why it is so valuable when the CEO of one of the most successful businesses in world economic history, picked for his job by one of the legendary superstars of commerce and technology, tells the world that he was one of "them."

I know an aversion to being illogical is never an absolute obstacle to bigotry. But I also know that thanks to Mr. Cook, simultaneously being one of the devoted fans of Apple and also a believer that there is something inferior about gay people has become much harder.

Read MoreThank you, Tim Cook

Some have criticized Cook for what he did. "Why does he have to talk about it?," they complain. The best answer is itself a demonstration that we have not yet achieved full social and legal equality. We LGBT people do not discuss our sexuality any more than the straight majority. The difference is that when we do it, it's labeled as something special, called "coming out." When they do it, it's something routine, called "talking."

Tim Cook has advanced the day when that distinction will no longer exist.

Commentary by Barney Frank, chair of the House Financial-Services Committee from 2007 to 2011, during which time Congress enacted the TARP program and the financial-reform bill known as Dodd-Frank. Follow him on Twitter@BarneyFrank.

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