It was through jealousy and envy that the greatest and most upright pillars of the Church were persecuted and struggled unto death. Let us set before our eyes the good apostles. First of all, Peter, who because of unreasonable jealousy, suffered not merely once or twice but many times, and, having thus given his witness, went to the place of glory that he deserved. It was through jealousy and conflict that Paul showed the way to the prize for perseverance. He was put in chains seven times, sent into exile, and stoned; a herald both in the east and the west, he achieved a noble fame by his faith. He taught justice to all the world and, when he had reached the limits of the western world, he gave his witness before those in authority; then he left this world and was taken up into the holy place, a superb example of endurance.
Around these men with their holy lives there gathered a great throng of the elect, who, though victims of jealousy, gave us the finest example of endurance in the midst of many indignities and tortures.
We are writing this, beloved, not only for your admonition but also as a reminder to ourselves; for we are placed in the same arena, and the same contest lies before us. Hence we ought to put aside vain and useless concerns and should consider what is good, pleasing and acceptable in the sight of him who made us. Let us fix our gaze on the blood of Christ, realizing how precious it is to his Father, since it was shed for our salvation and brought the grace of repentance to all the world.
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Pope Saint Clement I from a letter to the Corinthians