Los Angeles — Morgan Freeman has traveled more than 120,000 kilometers (more than 74,000 miles) and visited 30 cities to try to unravel mysteries of spirituality around the world.

Freeman said that on this long journey he understood that religion serves as "society's glue."

"In almost every society, whatever the religion is the point is to keep the people together functioning as a unit," he said.

The third season of a series on religion and belief, which has six episodes, premieres March 5 on National Geographic.

The series goes into great detail in its analysis of religion and rituals. — AFP