Abstract
The treatise on the Triune God is not just one more treatise among the others; it is the light, whose rays shed light on all theological questions. So it is rightly said of the Triune God that it is the “heart of Christian theology”, “the primal mystery of Christianity”, or “the first and last principle, the Alpha and Omega of the Christian life”. To say that God is a mystery, is to affirm that our knowledge will always remain on the threshold of knowledge, and only by analogy can we get closer to Him, but that does not prevent its influence from being decisive in our lives precisely as mystery of the Father, the Son and the Spirit. Our profession of faith confesses two aspects -inextricably linked- of the Christian God: on the one hand, monotheism (God is one and unique) as a legacy of the revelation of the Old Testament, on the other, what is originally Christian because that one God is the Triune Father, Son and Holy Spirit.
