He was educated at the Augustine college in Brussels and at the University of Douai, graduating as a Licentiate in both civil and church law in 1651.

Christyn was appointed master of requests to the Great Council of Mechelen in 1667, and privy councillor in 1671.

Against the expansionist claims of the French king Louis XIV, Christyn published La Flandre défendue des fausses prétentions de la France (Flanders defended against France's false claims) in 1684.

He believed he had an ex officio seat on the Brussels Council of State, but the pro-French chief president Leo-Jan de Pape refused it in order to block all claims to priority from the Madrid body.

provinces belgiques, a historical chorography of the Low Countries that was published after his death, has been attributed to him, but also to his nephew, Jan Baptist Christyn the Younger.