My views don't just represent "Mormonism" by a long shot, but many other Christian belief systems. Adventists tend to believe in soul sleeping, but Catholics, most Protestants and especially the Eastern Orthodox all believe that when one dies, the spirit survives. First Century Christians certainly believed it despite what Adventists believe. There were many books and libraries that were discovered in the late 1800s, then the Dead Sea Scrolls and the Nag Hammadi library in 1947, and more later.
As for the atheistic view, Albert Camus repeatedly discussed suicide as a viable way out of a world of woe. Though he didn't commit suicide, he did change his views later in life and was contemplating the Catholic priesthood when he was killed in an automobile accident. I had a neighbor who was an atheist and when he developed inoperable cancer, he sent his wife out shopping, wrote a note telling her to contact my father and not go in the garage. He posted it on the door leading from the kitchen to the garage, went into the garage and blew his head off. Both he and his wife were members of the Hemlock Society and later his wife admitted that she expected him to do this.
But some people want to hang on whatever the cost. Others just don't want the hassle of living life. People can believe what they want about an afterlife, but my maternal grandfather saw friends and relatives who had passed before he passed on and my father, as I've said, told us he had seen and spoken to his mother. She had died in complete dementia and I recall how frustrating it was on my dad, who found it difficult to deal with her. But this wasn't the person who spoke to him. I've also read scores of other accounts that convince me there's a real afterlife. And some of these shows dealing with ghosts, I think, are on the level. Several teams have gone to St. Augustine's lighthouse in Florida, and they saw, heard and experienced very similar paranormal activity. Two teams actually saw movement as well as hearing voices and footsteps.
People who get burned by religion can become bitter and throw everything out with the bathwater. That's unfortunate. If one can just reject Adventism and not reject all religion, I think they'd be less bitter and find more purpose in life.
St. Augustine's Lighthouse in northeast Florida.