There are many movements who believed Jesus was coming in their lifetime, like the Millerites

There were hundreds of millions of people, who earnestly believed the Second Coming was happening in their lifetime. Some of these believed this with such firmness, they gave up their lives, sold everything, and waited for an event that never materialized. One example of this is the Millerite movement of the 19th century.

The Millerites were a Christian group that believed the Second Coming would happen in 1844. At its peak their movement was 30,000 – 100,000 strong. When the Second Coming did not happen as predicted, an event aptly called “The Great Disappointment”, many left the movement, while others reinterpreted the prophecies and founded the Seventh Day Adventist church.

This historical incident has served as a great illustrator of the psychological phenomenon called “cognitive dissonance reduction,” which is the act of reducing tension between beliefs (ex: “Jesus will come in 1844”) and evidence (ex: “Jesus did not come in 1844”) by introducing some new idea (ex: “Jesus did return, but it was an invisible event, to be interpreted differently”).

While it’s difficult for some to imagine how this group could believe something as incredulous, one must note that they believed this with a great deal of devotion, and suffered immense emotional difficulty coming to grips with reality. One can only read letters by Millerites of the Great Disappointment, to see the stringent emotional grief. As in the case of the letter from Henry Emmons, member of the Millerites movement

“I waited all Tuesday and dear Jesus did not come; I waited all the forenoon of Wednesday, and was well in body as I ever was, but after 12 o’clock I began to feel faint, and before dark I needed someone to help me up to my chamber, as my natural Strength was leaving me very fast, and I lay prostrate for 2 days without any pain – sick with disappointment.”