In 1974, Marshall Applewhite and Bonnie Nettles founded the infamous religious group called Heaven's Gate in San Diego, California.
They had met at a psychiatric hospital where she was working and he was a patient. Nettles told Applewhite that extraterrestrials had foretold that this meeting would happen and convinced him that he had a divine purpose. The two grew to believe that they were the two witnesses described in the Book of Revelation and that they were chosen to fulfill biblical prophecies and contact aliens, so they began recruiting followers, promising them that they'd be brought to a higher evolutionary level to overcome their "humanness."
Members sold their possessions and left their families to go underground with their newfound "family." The group believed that evil space aliens, which they called Luciferians, were tricking people into believing they were God and corrupting them. They were also convinced that a second coming was impending and that the only way to survive it was to "leave" by way of suicide.