In 1769, Collin graduated from Uppsala University with a Master of Philosophy and was ordained as a priest in the Church of Sweden, like his father.

[1] Collin was subsequently sent by the church to minister to its congregants in Britain's North American colonies in the same year, arriving there in 1770.

[5] After the American victory in the war led to the foundation of the United States in 1783, Collin was offered the opportunity to return to Sweden, though he declined.

Collin also demonstrated a fledgling interest in American politics, supporting conservative views as a member of the Federalist Party.

[1] When the Swedish pastor in New Castle County, Delaware died in 1791, Collin became sole Church of Sweden clergyman in the United States.