Gregory the Great — as excerpted in the Catena Aurea on Mark 8:34-38

“(Hom. 32. in Evang.) There are however some, who confess Christ, because they see that all men are Christians; for if the name of Christ were not at this day in such great glory, the Holy Church would not have so many professors. The voice of profession therefore is not sufficient for a trial of faith whilst the profession of the generality defends it from shame. In the time of peace therefore there is another way, by which we may be known to ourselves. We are ever fearful of being despised by our neighbours, we think it shame to bear injurious words; if perchance we have quarrelled with our neighbour, we blush to be the first to give satisfaction; for our carnal heart, in seeking the glory of this life, disdains humility.”