What causes oceanic tides to crest and fall? According to conservative opinion host Bill O'Reilly, it's a mystery.

It's not actually a mystery, but to the Republican Fox News Channel's favorite grouch, tidal movements are apparently proof positive that an invisible man is pulling the strings of reality.

He made the revealing statement during a recent segment of The O'Reilly Factor while challenging Dave Silverman, president of a group called "American Atheists." That same organization was responsible for a billboard in Huntsville, Alabama that calls out to atheists who may still be attending religious ceremonies.

"You KNOW they're all SCAMS," the sign reads, promoting a regional meeting of non-believers. "American Atheists: Telling the Truth since 1963."

O'Reilly, who claims to be a Christian and a "culture warrior" on a crusade against ideas and trends that displease him, took notice of the group's outreach and invited Silverman on the show.

Their discussion was nothing short of heated.

"I'll tell you why [religion is] not a scam," he said. "In my opinion -- alright? Tide goes in, tide goes out. Never a miscommunication. You can't explain that. You can't explain why the tide goes in."

Silverman looked befuddled. "Tide goes in, tide goes ... out?" he asked.

"See, the water, the tide-- it comes in and it goes out, Mr. Silverman," O'Reilly repeated. "It always goes in, then it goes out."

"Maybe it's Thor up on Mount Olympus who's making the tides go in and out," Silverman retorted.

"No-no-no!" the host objected. "You can't explain that. You can't explain it."

"A myth and religion are the same thing," Silverman said. "It doesn't matter that I can't explain it. It doesn't mean that an invisible magic man in the sky is doing it."

Of course, he can explain tidal movements, as can many 5th-8th grade students in US public schools.

In short, oceanic tides are caused by the moon's rotation around the earth, with inertia and gravity causing a sea swell as it passes. Scientists have measured the phenomenon in great detail, documenting two distinct tidal bulges that circle the earth as the moon sweeps around it.

But don't try telling that to O'Reilly.

A recent study by the University of Maryland found that extended exposure to the Republican Fox News Channel often resulted in voters believing patently false claims on key social and political issues.

This video is from the Republican Fox News Channel, broadcast Jan. 4, 2010.

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