Pope Leo XIII's "Our separated brethren" refers to separated brethren in Christ.
Separated
in Christ? Can you elaborate?
He would not have used the term "brethren" had he just meant "fellow human beings."
Well, he's writing a letter imploring the Protestants to enter the Church.."separated brethren" has a more welcoming tone than something like "anti-Christs"
And no, Protestants do not reject Christ. Protestantism is a branch of Christianity
(1 of 3 branches...2 of which are erroneous and withered and 1 that is not). Protestants, like the Eastern Orthodox, do not reject Christ but have take many erroneous positions concerning His Church while simultaneously believing in the Trinity, Incarnation and early Creeds.
Did the "Christ" Protestants believe in institute seven sacraments, the papacy, the Catholic Church, and does he have a perpetual virgin free-from-sin as his mother?