Raised as a Scottish Presbyterian, William MacDonald grew in his faith and sought opportunities to study. After closely examining the Bible and church history, he made the decision to leave the church of his ancestors and become a Baptist. So great was his desire to continue his studies in the faith, that he moved to London and enrolled as a preaching student under the leadership of Charles H. Spurgeon.

After his time with Spurgeon, William pastored in Scotland. He then ministered in the United States, where he was injured in a train wreck that left him lame and blind in one eye. Still, when he returned to Great Britain, he was able to read an ad in a London newspaper, signed by the ambassador to Chile. The ad asked for settlers to move to Chile and establish colonies. William saw this as an opportunity to bring the gospel to Chile, which had little evangelical influence. He moved his family and immediately began teaching and preaching. Mounting his trusted “preaching horse,” he traveled from village to village sharing the gospel.

Just two years after his arrival, civil war broke out in Chile. The colonists were allowed to stay, but guerrilla warfare made conditions very dangerous. Enduring the harsh conditions, William stayed with his family in Chile, faithfully trusting God in the coming years, and then decades. Thirty-one years of mission work in Chile would pass before William and his wife were appointed by the Foreign Mission Board in 1919.