Friendly Reminder From Augustine on Effectual Calling

Augustine: "When, therefore, the gospel is preached, some believe, some believe not; but they who believe at the voice of the preacher from without, hear of the Father from within, and learn; while they who do not believe, hear outwardly, but inwardly do not hear nor learn;—that is to say, to the former it is given to believe; to the latter it is not given. Because “no man,” says He, “cometh to me, except the Father which sent me draw him.” And this is more plainly said afterwards. For after a little time, when He was speaking of eating his flesh and drinking His blood, and some even of His disciples said, “This is a hard saying, who can hear it? Jesus, knowing in Himself that His disciples murmured at this, said unto them, Doth this offend you?” And a little after He said, “The words that I have spoken unto you are spirit and life; but there are some among you which believe not.” And immediately the evangelist says, “For Jesus knew from the beginning who were the believers, and who should betray Him; and He said, Therefore said I unto you, that no man can come unto me except it were given him of my Father.” Therefore, to be drawn to Christ by the Father, and to hear and learn of the Father in order to come to Christ, is nothing else than to receive from the Father the gift by which to believe in Christ. For it was not the hearers of the gospel that were distinguished from those who did not hear, but the believers from those who did not believe, by Him who said, “No man cometh to me except it were given him of my Father.” [source]

Addendum
John Calvin: "We now see why this exception was by the way introduced; it was, that no one might suppose that faith necessarily follows where there is preaching. He however does afterwards point out the reason, by saying, “To whom has the arm of the Lord been revealed?” by which he intimates that there is no benefit from the word, except when God shines in us by the light of his Spirit; and thus the inward calling, which alone is efficacious and peculiar to the elect, is distinguished from the outward voice of men. It is hence evident, how foolishly some maintain, that all are indiscriminately the elect, because the doctrine of salvation is universal, and because God invites all indiscriminately to himself. But the generality of the promises does not alone and by itself make salvation common to all: on the contrary, the peculiar revelation, mentioned by the Prophet, confines it to the elect." [source]