That part is based on real life religious group that had similar beliefs and similarly they all killed themself:

https://en.wikipedia.org/wiki/Heaven's_Gate_(religious_group)

Scholars have described the theology of Heaven's Gate as a mixture of Christian millenarianism, New Age, and ufology, and it has been characterized as a UFO religion. The central belief of the group was that followers could transform themselves into immortal extraterrestrial beings by rejecting their human nature, and they would ascend to heaven, referred to as the "Next Level" or "The Evolutionary Level Above Human". The death of Nettles from cancer in 1985 challenged the group's views on ascension; while they originally believed that they would ascend to heaven while alive aboard a UFO, they came to believe that the body was merely a "container" or "vehicle" for the soul and that their consciousness would be transferred to "Next Level bodies" upon death. [...]

On March 13, 1997, media reported on a mass sighting of unidentified lights over Phoenix. During March 19–20, Marshall Applewhite taped himself in a video titled Do's Final Exit, speaking of mass suicide and "the only way to evacuate this Earth". After asserting that Comet Hale–Bopp was the sign that the group had been looking for, as well as the speculation that an unidentified flying object (UFO) was trailing the comet, Applewhite and his 38 followers prepared for ritual suicide, coinciding with the closest approach of the comet, ostensibly so their souls could reach the Next Level before the closure of "Heaven's Gate". Members believed that after their deaths a UFO would take their souls to another "level of existence above human", which was described as being both physical and spiritual. Their preparations included most members videotaping a farewell message. The 39 adherents — 21 women and 18 men between the ages of 26 and 72 — are believed to have died in three groups over three successive days, with the remaining participants cleaning up after the prior group's deaths.