Baptists come from a long line of dissenters who oppose "Protestant privilege" - not because they're against Protestants, but because they support religious liberty for all people, Knox observes.
When many people talk about "freedom of religion," they mean they want government to allow them to freely exercise their religion, but they don't care about others' religion.
This has been the "Protestant privilege" for decades.
This perspective was posed to me recently, followed by the question, "What do you think?"
The issue isn't as simple as a bumper-sticker phrase. But "Protestant privilege" still reflects a trend that runs throughout U.S. history.
As soon as Europeans landed on these shores, Protestants dominated the culture. People say colonists traveled to America for religious liberty. Actually, they traveled here for their religious liberty, but nobody else's.
So, for example, Congregationalists ruled Massachusetts, while Anglicans ran Virginia, Quakers benevolently led Pennsylvania and Catholics held sway in Maryland.
Inspired by Enlightenment political theory, generations of religious wars in Europe and American religio-political dysfunction, the Founding Fathers included the religion clauses as the first 16 words of the First Amendment: "Congress shall make no law respecting an establishment of religion or prohibiting the free exercise thereof."
The idea was to keep government out of church business, either by sponsoring religion or interfering with it, and to keep religion from running government.
That's the civics lesson - the way things are supposed to be. The real world of politics and everyday life is messier.
Because Protestants historically outnumbered everyone else, they shaped public enterprises - government, religion, education, business and even sports and, to a lesser extent, entertainment.
The broadest example is the fact only one non-Protestant, John Kennedy, has been elected president.
For most of the 20th century, "Protestant privilege" favored people from Mainline Protestantism, such as Episcopalians, Methodists and Presbyterians. Most national leaders from that era, particularly in politics and business, were Mainliners.
The primary exception was the South, where Baptists - Protestants, whether they liked the term or not - dominated.
Beginning about 1980, the momentum shifted to evangelical Protestants.
They come from Baptists, nondenominational churches and the conservative branches of the Protestant denominations. They're the ones who have strived to stand at the center of American politics since the Moral Majority helped Ronald Reagan win the White House.
Today, "Protestant privilege" is associated with the First Amendment's religion clauses. Conservative Protestants particularly advocate for interpretations to go their way.
Until very recently, their emphasis had more to do with tweaking the Establishment Clause to allow government support for their ministries. For example, they wanted government-funded vouchers for Christian schools and government grants for community ministries.
Lately - especially in light of the Supreme Court's ruling on same-sex marriage - they want government to guarantee their free exercise of religion. Often, "religious liberty" is evangelical code for opposing Obamacare's contraception mandate and homosexual marriage.
Some Americans want their religious beliefs to be privileged in their businesses, not just in church and religious institutions.
Baptists come from a long line of dissenters who oppose "Protestant privilege" - not because they're against Protestants, but because they support religious liberty for all people.
Baptist Roger Williams founded Rhode Island as a safe haven for people of all faiths and no faiths.
Baptist John Leland convinced James Madison to include the religion clauses in the First Amendment.
Texas Baptists George W. Truett and James Dunn were two of the 20th century's greatest champions of religious liberty for all Americans.
"Protestant privilege" is a selfish, shabby substitute for religious freedom.
Marv Knox is field coordinator of Fellowship Southwest, a network that comprises CBF of Oklahoma, CBF of Texas and CBF West. He served previously as the editor and publisher of The Baptist Standard. A version of this article first appeared in The Baptist Standard. It is used with permission. You can follow him on Twitter @marvknox.