Forscutt joined the Mor­mon (LDS) Church as a 19-year-old in 1853, caus­ing his fa­ther to dis­own him and make him move out of his child­hood home. From 1855-60, Fors­cutt was a mis­sion­ary for the LDS Church in Eng­land.

In March 1860, he mar­ried fellow Latter-day Saint Eliz­a­beth Uns­worth. On their wed­ding day, he and his wife be­gan their move to Utah, in­tending to join the ga­ther­ing of Lat­ter-day Saints in Salt Lake Ci­ty. Up­on arriving, he be­came a sec­re­ta­ry to Brig­ham Young, pre­si­dent of the LDS Church. Short­ly after his ar­riv­al, Fors­cutt be­gan to learn about the LDS prac­tice of plur­al mar­ri­age, which he had not been aware of pre­vious­ly. This dis­cov­ery, com­bined with other dis­agree­ments with Brig­ham Young, led Fors­cutt to leave the LDS Church. He be­came af­fil­i­at­ed with a group led by Jo­seph Mor­ris; he was an apos­tle in the Mor­ris­ite or­gan­iz­a­tion and was in­volved in the 1861 Mor­ris­ite War. Aft­er these in­ci­dents, Fors­cutt joined the Unit­ed States Ar­my unit at Fort Doug­las in Salt Lake Ci­ty and was sta­tioned in Ru­by Val­ley (now Ne­va­da) be­fore re­turn­ing to Salt Lake Ci­ty.

In 1865, Fors­cutt joined the Re­formed LDS (RLDS) Church in Salt Lake Ci­ty. He soon left the ter­ri­to­ry, fear­ing for his life as an apost­ate from the LDS Church. Fors­cutt be­came a close per­son­al friend of Jo­seph Smith III, and lat­er served as a full-time mis­sion­a­ry for the RLDS Church in Eng­land and the So­ci­e­ty Islands. He was a co­py­ist in the pro­cess that led to the 1866 pub­li­ca­tion of the Jo­seph Smith Trans­la­tion of the Bi­ble in 1866. Fors­cutt com­posed a num­ber of hymns and ed­it­ed Saints’ Har­m­ony, an RLDS hymn­al pub­lished in 1889.