Attempting to flee Christian influences, he accepted the post of teacher and shochet at Plymouth. He taught Hebrew to the Rev. Benjamin Golding of Stonehouse church. In 1825, he converted to Christianity.
Soon afterwards, he and his wife, Deborah, went to live in Dublin, where he taught Hebrew and was ordained a priest in the Anglican Church in 1827. This was followed by working with CMJ, firstly in Danzig between 1827 and 1830, and then in London between 1831 and 1841.
Alexander's position was always a controversial one. He worked alongside the CMJ pioneer, John Nicolayson, in consolidating the Protestant presence in Jerusalem. Various institutions were set up under his leadership, including a School of Industry for training Jewish believers in basic trades, an Enquirers House, a Hebrew College, and a modern hospital for Jewish people. His presence greatly antagonised the Jewish leadership, as well as provoking the other major churches to consolidate their presence in Jerusalem. Both the Roman Catholic church and Greek Orthodox church subsequently sent Patriarchs to Jerusalem to counteract Alexander's influence.
He died in Bilbeis, Egypt while returning to England. He was buried in Jerusalem.
