A Letter to Rome examines Charles Hodge’s 1869 response to Pope Pius IX and the First Vatican Council, a rare moment when American Presbyterianism spoke directly to Rome. With clarity and charity, Hodge explains why the core issues of the Reformation — Scripture alone, the sufficiency of Christ, and the nature of church authority — made unity impossible. This episode revisits that letter and asks what modern Protestants can learn from Hodge’s firm convictions and pastoral tone in an age of renewed ecumenical pressure.