After brilliant studies at the St Michael College, Brussels, Pierre entered the noviciate of the Society of Jesus on 23 September 1899, at Tronchiennes.

His original approach and ideas crystallized in his best-selling book of meditations: ‘La prière de toutes les heures’, published in 1924.

From 1923, responding to requests coming from the Lemfu Seminary - first ever training centre for seminarians of the Belgian Congo - Charles launches the "Xaveriana" collection, a series of pamphlets that dealt with aspects of missionary life and activities, starting with down-to-earth pastoral issues: polygamy, sorcery, etc.

Pius XI continued his efforts and, by consecrating the first indigenous bishops in Africa, China, India, indirectly approved these ideas of Charles.

In response to multiple requests, he travelled a lot, and his knowledge of mission lands and their peoples taught him how to collaborate with national and international agencies.

He was a distinguished professor and theologian, lecturer and writer, and acknowledged as a Missiology pioneer, particularly in the French speaking area of Europe, and founder of partnerships to assist mission initiatives.