Do you believe in the apparition of Mary to certain people (in Fatima etc.)? Is this possible?

Answer: Neither the “Catechism of the Catholic Church” nor the “German Adult-Catechism of the German Bishops Conference” says anything about the belief in apparitions of Mary. They are not part of the official, salvation teachings of the Church. They are an expression of the charismatic-mystical gifts of the Church. They occur within the person’s own conscious and are imagination or are based on imaginative visions. Unlike physical appearances, where the senses experience an external stimulus, apparitions of Mary are better described as an intense expression of faith which is combined with extraordinary sensations and experiences. In the history of the Church, there are many stories of highly impressive religious experiences of this kind, which frequently resulted in conversion. […]

The phenomenon of apparitions of Mary occurs mostly among simple believers and lay people, who thus represent a positive challenge to the Church. The conflict between the two arises largely from the fact that the supernatural character of such events cannot be proven simply by stating that it is so. Rather, a number of criteria have to be taken into account when looking at private revelations.

Criteria: 1. health and moral integrity of the visionary. To aid discernment mystical theology refers to the classic virtues: truthfulness, sobriety, humility, peacefulness, love and modesty. Modern ways of assessment which have been augmented by psychology, also consider the moral life of the visionary. 2. it has to be ascertained whether the alleged vision corresponds with the teachings of Holy Scriptures and the faith of the Church. Not only do possible contradictions have to be noted, but also whether the traditional emphases have been maintained, and the biblical faith has not been converted into, for example, a threatening message. Because, the Christian revelation has at its absolute core the person of Jesus Christ, all subsequently given graces can only make sense, if they bring this fact to life. Apparitions of Mary are thus not to be seen as additions to the biblical word, but as an impulse, to clarify and to live the original revelation of Jesus Christ within a specific time in history. […]

An evaluation according to these criteria can result in the rejection of the alleged apparition by a local bishop or the Holy See. […] Even where a positive evaluation has been made, believers retain a high degree of freedom whether to accept the verdict. It can be accepted with a human faith, which follows the rules of judiciousness, while theological faith which refers to holy truths is not necessary. Respectful rejection and critical distance remain possible. … (Franz Courth, art. “Marienerscheinungen“, in: Praktisches Lexikon der Spiritualität, hg. Christian Schütz. Freiburg, 1988.)