The quotation below is found in the new Reformation issue of The Standard Bearer (October 15, 2014), a Reformed semi-monthly magazine published by the Reformed Free Publishing Association. This special issue is devoted to the church father Augustine, and the opening meditation is an excerpt from a sermon (homily) of Augustine based on John 10:1-10.
Notice how the doctrines of sovereign grace permeate what he says in this section while acknowledging the mixed nature of the church in this present world.
12. You hear, brethren, the great importance of the question. I say then, “The Lord knoweth them that are His.” He knoweth those who were foreknown, He knoweth those who were predestinated; because it is said of Him, “For whom He did foreknow, He also did predestinate to be conformed to the image of His Son, that He might be the firstborn among many brethren. Moreover, whom He did predestinate, them He also called; and whom He called, them He also justified; and whom He justified, them He also glorified. If God be for us, who can be against us?” Add to this: “He that spared not His own Son, but delivered Him up for us all, how hath He not with Him also freely given us all things?”
But what “us”? Those who are foreknown, predestinated, justified, glorified; regarding whom there follows, “Who shall lay anything to the charge of God’s elect?” Therefore “the Lord knoweth them that are His;” they are the sheep. Such sometimes do not know themselves, but the Shepherd knoweth them, according to this predestination, this foreknowledge of God, according to the election of the sheep before the foundation of the world: for so saith also the apostle, “According as He hath chosen us in Him before the foundation of the world.”
According, then, to this divine foreknowledge and predestination, how many sheep are outside, how many wolves within! and how many sheep are inside, how many wolves without! How many are now living in wantonness who will yet be chaste! how many are blaspheming Christ who will yet believe in Him! how many are giving themselves to drunkenness who will yet be sober! how many are preying on other people property who will yet freely give of their own! Nevertheless at present they are hearing the voice of another, they are following strangers.
In like manner, how many are praising within who will yet blaspheme; are chaste who will yet be fornicators; are sober who will wallow hereafter in drink; are standing who will by and by fall! These are not the sheep. (For we speak of those who were predestinated,—of those whom the Lord knoweth that they are His.) And yet these, so long as they keep right, listen to the voice of Christ. Yea, these hear, the others do not; and yet, according to predestination, these are not sheep, while the others are.