In order to address the theme of definitive affirmations and the relative in the ecclesial Magisterium, the author will attempt, firstly, to examine the need for a discernment of what pluralism, both absolute and relative, is (1), and then to say a few words about theology and the Magisterium, at the service of the transmission of Christian revelation (2). Afterwards, the theme of the Magisterium as a task of the entire Church will be treated (3), and its understanding (misunderstanding) in a globalized world (4). Finally, the author will offer some illuminating thoughts from the reflections of Karl Barth (5) and of Walter Kasper (6) and the necessity of an adequate "Magisterial hermeneutic" (7). With this insight, the necessary complementarity of the pronouncements of Vatican I and Vatican 11 regarding the definitive and the relative in the ecclesial Magisterium will be explored (8). The author will present an example from the Declaration of the Congregation for the Doctrine of the Faith Dominus lesus, on the unicity and the salvific universality of Jesus Christ and of the Church (9). Finally, the author will formulate a conclusive summary. (10) The Magisterium is a service to the Church and to the revelation of God, who, in Christ, has manifested Himself as fullness. It must always be a process of thought, and exercised, within a spirituality of ecclesial commmunion, in an admirable agreement between faithful and pastors, fruit of the action of the Spirit. The "irreformability" of the essential truths in the Church does not mean that they are "unreformable". There is a margin of reformulation that is not irrelevant, although this reformulation cannot have a contrary sense. That means listening devoutedly, guarding scrupulously, and explaining faithfully what is transmitted, as Vatican reminds us in the Constitution on Divine Revelation. It is a service rather than a dominion, a ministry and not a power, conducted in company with the whole believing people, with the sense of faith and other services in the transmission of revelation. In short, the author will be examining nothing less that the profound conviction that Christ, by the strength of the Spirit, continues to live and be present in the Church of God.