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Pergunta: Com que idade Joseph Smith tornar-se preocupado com a religião?
Question: At what age did Joseph Smith become concerned about religion?
Joseph's interest in religion began when he was 12 years old, after the 1817 revival
Joseph's concern about religion started when he was twelve years old, close on the heels of the revival of 1817. In his 1832 account, Joseph notes that his concern about religion began at age 12 (1817-1818):
"At about the age of twelve years my mind become seriously imprest with regard to the all importent concerns of for the wellfare of my immortal Soul which led me to searching the scriptures believeing as I was taught, that they contained the word of God thus applying myself to them and my intimate acquaintance with those of different denominations led me to marvel excedingly for I discovered that they did not adorn instead of adorning their profession by a holy walk and Godly conversation agreeable to what I found contained in that sacred depository this was a grief to my Soul..." (Joseph Smith's 1832 account of the First Vision)
Richard Bushman notes that this "would have been in late 1817 and early 1818, when the after-affects of the revival of 1816 and 1817 were still felt in Palmyra." 
Joseph Smith talked of observing, as a 14-year-old, "an unusual excitement on the subject of religion" in the Palmyra area during the Spring of 1820. Joseph notes that "It commenced with the Methodists, but soon became general among all the sects in that region of country." There is documented evidence of at least one Methodist camp meeting in the Palmyra area during that period, which only by chance happened to be mentioned in the local newspaper because of a specific death that seemed to be associated with it. In addition, there are newspaper articles talking of large-scale revival activity in the larger region surrounding Palmyra during the same general period when Joseph Smith said that it was taking place.
It is reasonable to assume based upon the facts that the Methodists had more than one camp meeting during this period. This could easily account for the religious excitement in Palmyra that, in Joseph's mind at age 14, began with the Methodists.
From age 12 to 15 Joseph pondered many things in his heart concerning religion
Joseph continues in his 1832 account: "[T]hus from the age of twelve years to fifteen I pondered many things in my heart concerning the sittuation of the world of mankind the contentions and divi[si]ons the wicke[d]ness and abominations and the darkness which pervaded the of the minds of mankind my mind become excedingly distressed for I become convicted of my sins." In July, 1819, several years after Joseph said his mind became "seriously imprest," a major Methodist conference was held near Palmyra:
[T]he Methodists of the Genesee Conference met for a week in Vienna (later Phelps), a village thirteen miles southeast of the Smith farm on the road to Geneva. About 110 ministers from a region stretching 500 miles from Detroit to the Catskills and from Canada to Pennsylvania met under the direction of Bishop R. R. Robert to receive instruction and set policy. If we are to judge from the experience at other conferences, the ministers preached between sessions to people who gathered from many miles around. It was a significant year for religion in the entire district. . . . The Geneva Presbytery, which included the churches in Joseph's immediate area, reported in February, 1820, that "during the past year more have been received into the communion of the Churches than perhaps in any former year." Methodists kept no records for individual congregations, but in 1821 they built a new meetinghouse in town. 
- Richard L. Bushman, Joseph Smith and the Beginnings of Mormonism (Urbana and Chicago, Illinois: University of Illinois Press; Reprint edition, 1987), 53. ISBN 0252060121.
- Bushman, Beginnings of Mormonism, 53.