4 But as I have said, let us leave these, and attend rather to these our brethren, with whom we have to do. For Christ is the Head of the Body. The Head is in Heaven, the Body is on earth; the Head is the Lord, the Body His Church. But ye remember it is said, “They shall be two in one flesh.” “This is a great mystery,” says the Apostle, “but I speak in Christ and in the Church.” If then they are two in one flesh, they are two in one voice. Our Head the Lord Christ spoke to the Jews these things which we heard, when the Gospel was being read, The Head to His enemies; let the Body too, that is, the Church, speak to its enemies.
You know to whom it should speak. What has it to say? It is not of myself that I have said, that the voice is one; because the flesh is one, the voice is one. Let us then say this to them; I am speaking with the voice of the Church. O Brethren, dispersed children, wandering sheep, branches cut off, why do ye calumniate me? Why do ye not acknowledge me? “Search the Scriptures, in which you think you have eternal life, they testify of me;” to the Jews our Head says, what the Body says to you; “You shall seek me, and shall not find me.” Why? Because ye do not “search the Scriptures, which testify of me.”
Source: Sermons on Selected Lessons of the New Testament (New Advent)