Fascinating. Via Capital Public Radio:
Not long after the British-made film landed in the United States,
"submarine churches" attracted urban, young people. They adopted the
outline of a yellow submarine with a small cross on its periscope as their symbol and displayed it alongside peace signs, flowers and other popular emblems of the 1960s.
There were enough of the churches a year after the film's release
that they operated The Submarine Church Press, which published a
national directory of 40 such churches, most with mainline Protestant or
Catholic roots, and held a three-day "rap session," or conference, in
Kansas City, Mo. Attendees came from New York, Los Angeles, San
Francisco, Chicago, St. Louis and Akron, Ohio.
"In the Beatles' movie, the submarine was the place where they
loved each other in a groovy way and got strength to do battle with the
Blue Meanies," Rev. Tony Nugent, a former co-pastor of a submarine
church in Berkeley, Calif., told The New York Times in 1970. "It also shows that a church has to have flexibility and maneuverability."
... "The Beatles viewed love and peace as the highest values in living a good life," said Hector Avalos,
a professor of religious studies at Iowa State University who has
written about the Beatles and religion. "Living a good life was not
about salvation or following the Bible. That emphasis on love erased all
the 'isms' that Lennon specifically hated."