Original: Joseph Smith , Jr. ( December 23 , 1805 -- June 27 , 1844 ) was the founder of the Latter Day Saint movement , also known as Mormonism , and an important religious and political figure during the 1830s and 1840s .
Simplified: Joseph Smith , Jr. ( b. 23 December , 1805 -- June 27 , 1844 ) was the founder of Mormonism .