Communicatio in Sacris is a Compendium of Roman Catholic Doctrine on the subject of Intercommunion with non-Catholics. This book produces the overwhelming theological consensus for the Dogmatic Teaching condemning Intercommunion with non-Catholics, putting together a treasury of Sacred Scriptures, Church Fathers, Doctors, Saints, Theologians, and Popes who have written on the matter. This book also covers the Theological Controversies, Scandals, and Hypocrisies of how so-called Traditionalist Catholics and pseudo-Orthodox have openly communicated in the sacred with those they consider the Heterodox and yet have tried to justify their actions. This book, not only reveals their crimes, but it opens the door for anyone to understand what the Roman Catholic Church has always taught on the subject, namely, that it is forbidden for Catholics to join non-Catholic Communion.