Steven Pinker’s ad endorsing the Freedom From Religion Foundation will air nationally today, Tuesday and Wednesday on CBS’ “The Late Show with Stephen Colbert,” 11:35 p.m. Eastern.

The distinguished Harvard professor and best-selling author urges viewers to join FFRF in its fight to prevent religion from creeping into U.S. government. Pinker has served as FFRF’s first honorary president since 2013. His newest book is Enlightenment Now: The Case for Reason, Science, Humanism and Progress.

The ad debuted in January in about 18 regional markets during “The Late Show.” In February, CBS agreed to run the ad nationally. This will be the first time an FFRF commercial has aired nationally on CBS since 2012. FFRF’s ad featuring John F. Kennedy’s famous remarks as a candidate endorsing the separation of state and church was shown then on “CBS News Sunday Morning” and the “Nightly News.” However, CBS has refused to broadcast FFRF’s commercial featuring Ron Reagan, in which he describes himself as “an unabashed atheist, not afraid of burning in hell.”

“The world has become a better place, as reason has been overcoming superstition and tribalism. But the values of the Enlightenment are under attack,” says Pinker in the current ad. “Please join me in supporting the Freedom From Religion Foundation to ensure that our government is driven not by religion, but by reason.”

The Freedom From Religion Foundation is flattered to receive the affirmation of such a leading global intellectual.

“We’re delighted and honored to have Steve’s endorsement fresh off the success of his powerful book, Enlightenment Now,” says FFRF Co-President Annie Laurie Gaylor. “We hope this campaign prompts secular Americans of all stripes to join FFRF at a critical time, as religious zealots are occupying our highest offices and courts.”

Pinker is one of the world’s premier intellects and cognitive psychologists, and serves as the Johnstone Family Professor of Psychology at Harvard University. He’s been named on the Time 100 list of the world’s “Most Influential People.” Among his other popular books are The Blank Slate, The Language Instinct and How the Mind Works.

With more than 31,000 members, FFRF, a 501(c)(3) nonprofit, works as a watchdog to protect the constitutional principle of the separation of state and church. For 40 years, FFRF has served as a leading voice for freethought in America. For more information, visit www.FFRF.org.