Machen was born in Baltimore on July 28, 1881. His father, a Baltimore lawyer, was 45 and Mary, his mother, was 24 when they married. While Arthur was an Episcopalian, Mary was a Presbyterian, and taught her son the Westminster Shorter Catechism from an early age. The family attended Franklin Street Presbyterian Church. Machen attended a private college and received a classical education including Latin and Greek. He also learnt to play the piano.