Separated brethren is a term sometimes used by the Catholic Church and its clergy and members to refer to baptized members of other Christian traditions. 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 Catholic Church had officially referred to Protestants and other 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 Since at least the mid-1990s, the term has often been replaced by Catholic officials with phrases such as "other Christians".
At least one Catholic writer did not consider Mormons and members of some other religious groups to be separated brethren. Among the groups William Whalen did not consider to be separated brethren were "Jews, Mormons, Christian Scientists, Muslims, Buddhists, and other groups."
During a period of lessening tensions with Jewish groups, Pope John Paul II once referred to Jews as "elder brothers in the faith of Abraham", prior to a 1987 visit to the United States.