Neil deGrasse Tyson sparked an internet furor after tweeting a birthday wish to Sir Isaac Newton — on Christmas day.

The Tweet, which has been shared more than 72,000 times, thrilled some with his wit and infuriated others, who thought it was disrespectful to those celebrating the birth of Jesus Christ.

He didn’t stop there. The astrophysicist, cosmologist, author, and science communicator kept the anti-Christian sentiments rolling.

And on Friday, Tyson wrote a Facebook message explaining his tweet, which he said is his most retweeted ever.

“Everybody knows that Christians celebrate the birth of Jesus on December 25th,” Tyson wrote. “I think fewer people know that Isaac Newton shares the same birthday. Christmas day in England – 1642. And perhaps even fewer people know that before he turned 30, Newton had discovered the laws of motion, the universal law of gravitation, and invented integral and differential calculus.”

On this day long ago, a child was born who, by age 30, would transform the world. Happy Birthday Isaac Newton b. Dec 25, 1642

— Neil deGrasse Tyson (@neiltyson) December 25, 2014

QUESTION: ThIs year, what do all the world's Muslims and Jews call December 25th? ANSWER: Thursday

— Neil deGrasse Tyson (@neiltyson) December 25, 2014

Merry Christmas to all. A Pagan holiday (BC) becomes a Religious holiday (AD). Which then becomes a Shopping holiday (USA).

— Neil deGrasse Tyson (@neiltyson) December 25, 2014

Tyson also addressed accusations that he is anti-Christian, saying, “If a person actually wanted to express anti-Christian sentiment, my guess is that alerting people of Isaac Newton’s birthday would appear nowhere on the list.”