Hilary of Poitiers

This episode in the Old Testament is a series of important types [sacramenta] of future spiritual events. The harlot takes into her house the two spies sent by Jesus [Joshua] to survey the land. The church, which was a sinner, receives the law and the prophets, sent to spy out the faith of men, and acknowledges that “God is in heaven above and on the earth beneath.” She receives from these same spies the scarlet sign of salvation, a color which is manifestly the color of royalty when considered as a dignity, and, when looked at, the color of blood. Both these features were found in the passion—the Lord was clothed in scarlet, and blood flowed from his side. Manasseh also received scarlet as a sign. The dwellings in Egypt marked with blood were spared, and with blood the book of the covenant was sprinkled and the people sanctified. Every member of the family found outside the house was guilty—a lesson that those apart from those called are responsible for their own death.