After very briefly falling out of religion, William Miller came back in a big way. Not only did he throw himself into preaching the Lord's gospel, but he also devoted his life to decoding what he believed was the Bible's secret code. You can guess how that turned out. 

Sources: 

Great Disappointment. Wikipedia. Last accessed on July 21, 2020. https://en.wikipedia.org/wiki/Great_Disappointment

The End of the World Was Almost Today in 1843 and 1844: The Failed Prophecies of the Millerites. Vermont Digital Newspaper Project. March 21, 2015. http://library.uvm.edu/vtnp/?p=2765

William Miller Convinced Thousands of Millerites The End was Near. New England Historical Society. 2019. https://www.newenglandhistoricalsociety.com/william-miller-convinced-thousands-millerites-world-end/