From the Catecheses by Saint John Chrysostom, bishop
The power of Christ’s blood

If we wish to understand the power of Christ’s blood, we should go back to the ancient account of its prefiguration in Egypt. Sacrifice a lamb without blemish, commanded Moses, and sprinkle its blood on your doors. If we were to ask him what he meant, and how the blood of an irrational beast could possibly save men endowed with reason, his answer would be that the saving power lies not in the blood itself, but in the fact that it is a sign of the Lord’s blood. In those days, when the destroying angel saw the blood on the doors he did not dare to enter, so how much less will the devil approach now when he sees, not that figurative blood on the doors, but the true blood on the lips of believers, the doors…