Updated and slightly revised in 2012, "Communicatio in Sacris- Communion in the Sacred, " in Latin, is the only Book in the World that documents, details and quotes from numberless scholarly sources on why the Roman Catholic Church has always prohibited Catholics from intercommunicating with non-Catholics. The premise of this work explores the "so-called" mutual-lifting of the 1054 A.D. anathemas "revoked" by Paul VI and Athenagoras I, in 1965. In addition, it exposes the hypocrisies of so-called Traditionalist(s) in the Orthodox and Catholic movements in regards to Intercommunion such as the Russian Orthodox Church Outside of Russia, the Society of Pius X, the Center for Traditionalist Orthodox Studies in Etna, California, the Society of Pius V, the CMRI headed by Pseudo-Bishop Mark A. Pivarunas, the Most Holy Family Monastery headed by Brothers Michael and Peter Dimond, the Saint Benedict Center of Richmond, New Hampshire headed by Brother Andre Marie, and many others.