Why Catholic can't be mason?

Answer 1

Roman Catholic AnswerBecause the two are incompatable, like asking why a Catholic can't be a protestant. In the latter case, a Catholic can't be a protestant, because a protestant's reason for being is that they protest the Church. The Masons exist as an anti-Catholic organization. Some specific lodges are not overtly anti-Catholic, but the organization as a whole has been historically very anti-Catholic and has been condemned by every Pope for a couple centuries now.

from Modern Catholic Dictionary by John A. Hardon, S.J. Doubleday & Co., Inc. Garden City, NY 1980

Freemasonry. The teachings and practices of a secret international organization whose modern origins date from the first quarter of the eighteenth century. It defines itself as "the activity of closely united men who, employing symbolical forms borrowed principally from the mason's trade and from architecture, work for the welfare of mankind, striving morally to ennoble themselves and others and thereby to bring about a universal league of mankind." Freemasonry began as a fraternity of Deists in Europe, and its basic orientation has been naturalistic, i.e., anti-supernatural, ever since. The hostility of Masonic lodges to the Catholic Church has evoked numerous declarations of the Holy See, notably of Popes Clement XII (1738), Benedict XIV (1751), Pius IX in several documents, especially the Syllabus of Errors (1864), AND Leo XIII in the encyclical Humanum Genus (1884). The Code of Canon Law (1018) decreed that no Catholic may join Masonic sects or any other similar associations which plot against the church (Canon 2335). Since not all Masonic lodges are professedly anti-Catholic, a decision of the Sacred Congregation for the Doctrine of the Faith mitigated the severity of the existing law, stating: "In considering particular cases, it must be remembered that penal law is always subject to strict interpretation. Therefore one may safely teach and apply the opinion of those authors who hold that Canon 2335 refers only to those Catholics who join associations which plot against the Church" (September 18, 1974). In special cases, then, a lay Catholic may belong to a Masonic lodge, but the clergy, religious, and members of secular institutes may not belong.