The verbal jousting began when Joy Behar mentioned watching a History Channel show on the Greek philosopher Epicurus and his definition of happiness.
"Keep in mind that probably when [Epicurus] was around, there was no Jesus Christ stuff going on," co-host Whoopi Goldberg said.
"They still had Christians back then," Shepherd interrupted.
"They had gods," Goldberg said.
"They had Christians," Shepherd insisted. "And they threw 'em to the lions."
"I think this might predate that," Goldberg said.
"I don't think anything predated Christians," Shepherd shot back.