For my part, I should not believe the gospel except as moved by the authority of the Catholic Church. So when those on whose authority I have consented to believe in the gospel tell me not to believe in Manichæus, how can I but consent? Take your choice. If you say, Believe the Catholics: their advice to me is to put no faith in you; so that, believing them, I am precluded from believing you—If you say, Do not believe the Catholics: you cannot fairly use the gospel in bringing me to faith in Manichæus; for it was at the command of the Catholics that I believed the gospel;— Again, if you say, You were right in believing the Catholics when they praised the gospel, but wrong in believing their vituperation of Manichæus: do you think me such a fool as to believe or not to believe as you like or dislike, without any reason? It is therefore fairer and safer by far for me, having in one instance put faith in the Catholics, not to go over to you, till, instead of bidding me believe, you make me understand something in the clearest and most open manner. To convince me, then, you must put aside the gospel. If you keep to the gospel, I will keep to those who commanded me to believe the gospel; and, in obedience to them, I will not believe you at all. But if haply you should succeed in finding in the gospel an incontrovertible testimony to the apostleship of Manichæus, you will weaken my regard for the authority of the Catholics who bid me not to believe you; and the effect of that will be, that I shall no longer be able to believe the gospel either, for it was through the Catholics that I got my faith in it; and so, whatever you bring from the gospel will no longer have any weight with me. Wherefore, if no clear proof of the apostleship of Manichæus is found in the gospel, I will believe the Catholics rather than you."
-St. Augustine, Against the Fundamental Epistle of Manichaeus, 5
So, was Augustine espousing the correct view of the Catholic church when he said that “We know that God’s grace is not given to all men . To those to whom it is given it is given neither according to the merits of works, nor according to the merits of the will, but by free grace. To those to whom it is not given we know that it is because of God’s righteous judgment that it is not given.” (Augustine, Treatise On Rebuke and Grace), or is he a heretic of the Catholic church?
If he is to be believed, then what he has said above was “moved by the authority of the Catholic Church.” It appears that the Church’s teaching has changed, or Augustine was lying when he said he was “moved by the authority of the Catholic Church.”
“The question has been proposed: Is the Church of Christ among the Catholics or among the Donatists? This needs to be determined from specific and clear citations in Holy Scripture. First, evidence is brought forth from the Old Testament and then from the New Testament.” (Augustine, Introduction, On the Unity of the Church)
"But, as I had begun to say, let us not listen to “you say this, I say that” but let us listen to “the Lord says this.” Certainly, there are the Lord’s books, on whose authority we both agree, to which we concede, and which we serve; there we seek the Church, there we argue our case" (Chapter 5)
More here: http://beggarsallreformation.blogspot.com/2014/12/augustines-unity-of-church-finally.html