Bernhard Welte was a thinking, philosophizing theologian. The present volume brings together his most significant contributions to the Mysteria fidei: on the nature of belief in God, on Christology and its understanding, on the Church as a community of faith, on the Eucharist and the veneration of saints, as well as on the Church's mission and proclamation to the world. Surprising insights emerge everywhere. Their essence: The mysteries of faith are the path of humanity toward its fulfillment and humanity. Faith proves to be a spiritual form of the free, rational, and at the same time, embodied, historical nature of man.