Leading alternative medicine advocate and physician, Deepak Chopra is offering $1 million to atheists who can define how human beings form ideas.

Chopra said the offer is not a joke, and he is looking for a scientific explanation of how an independent thought is formed.

"I'm revisiting my million dollar challenge to the 'Non-Amazing Randi' and his tribe of militant, new atheists," Chopra said in a YouTube video posted on Monday. Atheist and scientific skeptic James Randi is also known as "The Amazing Randi."

"Apparently my last offer – my last million dollar challenge – was a little intellectually challenging to the Non-Amazing Randi, and also to [famed evolutionary biologist and atheist] Richard Dawkins, and many others," Chopra continued. "So I'm revisiting it, and making it simpler."

His first million dollar challenge, issued last month, offered the bounty to "any skeptic who could prove how electrochemical activity in the brain produces the appearance of a three-dimensional world," and was in response to the James Randi Educational Foundation's "One Million Dollar Paranomal Challenge."

Randi's challenge offers one million dollars to anyone who can demonstrate a paranormal ability, such as being psychic. Over 1,000 people have accepted the challenge since it was first issued in 1964, but none have succeeded.

Chopra's new challenge specifically names Randi, Dawkins, and atheist scientist and philosopher Daniel Dennett as proposed challengers. The contest is to find "the biological basis of first-person experience."

"I'll even make it more simple," Chopra said. "Can you offer a scientific understanding for the biological basis of an idea? A thought?

"Just any thought. Forget the complexities of thought, including insight, intuition, imagination, creativity, choice, etc."

The physician's goal is to "defend the truth of spirituality," he wrote in an article for the Huffington Post. "The world's wisdom traditions are just as precious as science."

Neither Hawkins, Randi, or Dennett have issued a response to the new challenge.

See Chopra explain the challenge in the video below: