Coelde was born at Münster, made his first studies at Cologne, and entered the Order of the Hermits of St. Augustine at an early age. In 1454 he was received into the Franciscan Order in the Netherlands. When the plague broke out at Brussels in 1489, Coelde ministered to the dying. Before the end of the plague, more than thirty-two thousand had received the last rites from him.
Coelde died at Leuven, aged 80. In 1618 his remains were exhumed, and, after the suppression of the Franciscan convent at Leuven, were transferred to Sint-Truiden, where they now repose behind the high altar.
In 1470 Coelde composed a brief, popular treatise on the Catholic Faith, entitled "Kerstenspiegel" or "Christenspiegel" (The Christian's Mirror), which is considered to be the first German catechism. It went through thirty-two editions in Low German and two in High German, and came to be used throughout Germany and the Netherlands as the principal work of popular instruction in religious matters. At the request of his friend and admirer, Archbishop Hermann, he wrote a series of meditations on the sufferings of Christ, which appeared probably about the same time as the "Christenspiegel".
- SCHLAGER, Beiträge zur Geschichte der kölnischen Franziskaner-Ordensprovinz (Cologne, 1904), 190, passim;
- SCHOUTENS, Martyrologium Minoritico-Belgicum
- Theodore of Münster, Theodore of Osnabrück; Derick, Dederick or Dieterich, Cölde. He was a different person from the Dominican, Theodore of Münster, and from the Augustinian, Theodore of Osnabrück; and was called Theodore von Münster (Theodoricus a Monasterio) from the place of his birth; and Theodore von Osnabrück from his father's native town.