Knapp attended Columbia College (graduated 1894) and Yale College (BD 1897). He served at the First Congregational Church in Southington, Connecticut (1897-1900); the Brick Presbyterian Church in New York City (assistant pastor, 1901-1903); and the Central Congregational Church, Worcester, Massachusetts (1908-1936). His works include: “Up The Chimney”, “Down The Chimney” and “The Christmas Dinner”.