I couldn’t begin to give the entire history of what happened in 1966 in this forum, but the notes for this video posted by YouTube user In The Life of … the Beatles are extensive and well done.

A short quote:

A furore occurred in August 1966 after John Lennon’s remark that The Beatles had become “more popular than Jesus” was quoted by American teen magazine Datebook. Lennon originally made the remark when English newspaper reporter Maureen Cleave interviewed him for her series on the lifestyles of the four individual Beatles. When published in the United Kingdom in March 1966, Lennon’s words provoked no public reaction.

The controversy erupted on the eve of the band’s 1966 US tour. The strength and scale of the reaction against the Beatles led their manager, Brian Epstein, to consider cancelling the tour for fear of their lives.”

And this is the whole of their…