In Catholicism, the marks of the Church are that she is
these words are taken from the second part of the Nicene creed, which is commonly prayed at every Mass and the tenents of which are generally accepted by mainline Protestant denominations.
I think, but have very little basis for this thought, that Protestant reformers ...
Every mark of every church is potentially a tall order. I'll count the major branches as Eastern Orthodox, Roman Catholic, Lutheran, Anglican, and Reformed.
Lutherans say that "The Church is the congregation of saints, in which the Gospel is rightly taught and the Sacraments are rightly administered" (Augsburg Confession, Article VII).
Roman Catholics ...
Mainly for historical interest, I point out Optatus, a bishop of Milevis in modern-day Algeria. In a work published some time around A.D.370, he wrote at length in opposition to Parmenianus, the bishop of Carthage and leader of the Donatist movement.
Parmenianus claimed that there were six distinctive gifts of the true Church, and that Donatism possessed ...