Separated brethren is a term sometimes used by the Roman Catholic Church and its clergy and members to refer to baptized members of other Christian traditions.Also applied to Christians of the Eastern Orthodox and Oriental Orthodox churches. The phrase is a translation of the Latin phrase fratres seiuncti.
Before the Second Vatican Council, per the pronouncements of the Council of Trent, the Roman Catholic Church officially referred to Protestants and other non-Roman Catholic Christians as "heretics" likely not having hope of salvation outside of the "Church of Rome". However, Biblical passages like Romans 2:12-16 point to the importance of conscience in Catholic soteriology, which the Church has always recognized. In c. 1960 – c. 1962 preparation work for draft texts of Second Vatican Council documents, a "report urged respectful use of the terms dissidents or separated brethren, in place of heretics and schismatics." After the Second Vatican Council, however, "that habit of unthinkingly hurling accusations of heresy at Protestants pretty much died out". Since at least the mid-1990s, the term has often been replaced by Roman Catholic officials with phrases such as "other Christians".
At least one Roman Catholic writer does not consider Mormons and members of some other religious groups to be separated brethren. Among the groups not considered to be separated brethren are "Jews, Mormons, Christian Scientists, Muslims, Buddhists, and other groups." By the 21st century, within the Roman Catholic faith, Jews are described as and considered elder brothers in the faith.