Brian Cox is crapping on organized religion, and especially Christianity ... calling the Bible the worst book to ever grace human history, 'cause it's duped so many suckers and fools.

The "Succession" star sat for an interview with 'The Starting Line Podcast' ... and they talked about a lot of stuff -- including introspective thoughts on religion, God, spirituality, and all the rest. From Brian's POV ... it's all a bunch of hogwash, not buying any of it.

You can check out the full video to see his whole thought process -- but this clip here gets the job done ... with Brian explaining why society needs to move more toward a matriarchy.

He says the reason humans are so damn resistant to that, though, is because of the Bible -- and all the stories that go all the way back to Adam and Eve ... which he thinks subjugate women to a lesser-than role in society, and which are burned into our subconscious today.

On that front, BC calls the Bible the greatest propaganda instrument of all time -- and slams it as the worst book ever. He also says God doesn't exist ... and that religion is simply a means of control.

Safe to say ... the homeboy's an atheist, and he ain't down with all the praying and proselytizing. Sounds like Brian also thinks humans are being held back by old scribblings.