In the Catholic Church, there are many other things which most justly keep me in her bosom. The consent of peoples and nations keeps me in the Church; so does her authority, inaugurated by miracles, nourished by hope, enlarged by love, established by age. The succession of priests keeps me, beginning from the very seat of the Apostle Peter, to whom the Lord, after His resurrection, gave it in charge to feed His sheep (Jn 21:15-19), down to the present episcopate.
Saint AugustineGod will cleanse your sins if you yourself are dissatisfied with yourself and will keep on changing until you are perfect.
Saint AugustineSo you see how endlessly futile and fruitless it would be if we wanted to refute their objections every time they obstinately resolved not to think through what they say but merely to speak, just so long as they contradict our arguments in any way they can.
Saint Augustine