PART I: THE NECESSITY, POWER,
Chapter 1: The Necessity of Prayer, Section 1
Prayer is a Means Necessary to Salvation
One of the errors of Pelagianism was the assertion that prayer is not necessary for salvation. Pelagius, the impious author of that heresy, said that man will only be damned for neglecting to know the truths necessary to be learned. How astonishing! St. Augustine said: "Pelagius discussed everything except how to pray," [Da Nat. et Grat. c. 17] though, as the Saint held and taught, prayer is the only means of acquiring the science of the Saints; according to the text of St. James: "If any man wants wisdom, let him ask of God, Who giveth to all abundantly, and upbraideth not." [James 1: 5] The Scriptures are clear enough in pointing out how necessary it is to pray, if we would be saved. "We ought always to pray, and not to faint." [Luke 18: 1] "Watch and pray, that ye enter not into temptation." [Matt. 26: 41] "Ask, and it shall be given you." [Matt. 7: 7] The words "we ought," pray," "ask," according to the general consent of theologians, impose the precept, and denote the necessity of prayer. Wickliffe said, that these texts are to be understood, not precisely of prayer, but only of the necessity of good works, for in his system prayer was only well-doing; but this was his error, and was expressly condemned by the Church. Hence Lessius wrote that it is heresy to deny that prayer is necessary for salvation in adults; as it evidently appears from Scripture that prayer is the means, without which we cannot obtain the help necessary for salvation. [De just. lib. 2. c. 38, d. 3]
The reason of this is evident. Without the assistance of God's grace we can do no good thing: "Without Me, ye can do nothing." [John 15: 5] St. Augustine remarks on this passage, that our Lord did not say, "Without Me, ye can complete nothing," but "without Me, ye can do nothing;" giving us to understand, that without grace we cannot even begin to do a good thing. Nay more, St. Paul writes, that of ourselves we cannot even have the wish to do good. "Not that we are sufficient to think anything of ourselves, but our sufficiency is from God." [2 Cor. 3: 5] If we cannot I even think a good thing, much less can we wish it. The same thing is taught in many other passages of Scripture: "God worketh all in all. I will cause you to walk in My commandments, and to keep My judgments, and do them." [Ezek. 37: 27] So that, as St. Leo I says, "Man does no good thing, except that which God, by his grace, enables him to do," and hence the Council of Trent says: "If anyone shall assert, that without the previous inspiration of the Holy Ghost, and His assistance, man can believe, hope, love, or repent, as he ought, in order to obtain the grace of justification, let him be anathema." [Sess. 6, Can. 3]
The author of the Opus Imperfectum says, that God has given to some animals swiftness, to others claws, to other wings, for the preservation of their life; but he has so formed man, that God himself is his only strength." [Hom. 18] So that man is completely unable to provide for his own safety, since God has willed that whatever he has, or can have, should come entirely from the assistance of His grace.
But this grace is not given in God's ordinary Providence, except to those who pray for it; according to the celebrated saying of Gennadius. "We believe that no one approaches to be saved, except by the help of God; that no one merits this help, unless he prays." From these two premises, on the one hand, that we can do nothing without the assistance of grace; and on the other, that this assistance is only given ordinarily by God to the man that prays, who does not see that the consequence follows, that prayer is absolutely necessary to us for salvation? And although the first graces that come to us without any co-operation on our part, such as the call to faith or to penance, are, as St. Augustine says, granted by God even to those who do not pray; yet the Saint considers it certain that the other graces, and specially the grace of perseverance, are not granted except in answer to prayer: "God gives us some things, as the beginning of faith, even when we do not pray. Other things, such as perseverance, he has only provided for those who pray." Hence it is that the generality of theologians, following St. Basil, St. Chrysostom, Clement of Alexandria, St. Augustine, and other Fathers, teach that prayer is necessary to adults, not only because of the obligation of the precept [as they say], but because it is necessary as a means of salvation. That is to say, in the ordinary course of Providence, it is impossible that a Christian should be saved without recommending himself to God, and asking for the graces necessary to salvation. St. Thomas teaches the same: "After Baptism, continual prayer is necessary to man, in order that he may enter Heaven; for though by Baptism our sins are remitted, there still remain concupiscence to assail us from within, and the world and the devil to assail us from without." [P. 3, q. 39, a. 5] The reason then which makes us certain of the necessity of prayer is shortly this, in order to be saved we must contend and conquer: "He that striveth for the mastery is not crowned except he strive lawfully." [2 Tim. 2: 5] But without the Divine assistance we cannot resist the might of so many and so powerful enemies: now this assistance is only granted through prayer; therefore without prayer there is no salvation.
Moreover, that prayer is the only ordinary means of receiving the Divine gifts is more distinctly proved by St. Thomas in another place, where he says, that whatever graces God has from all eternity determined to give us, he will only give them if we pray for them. St. Gregory says the same thing: "Man by prayer merits to receive that which God had from all eternity determined to give him." Not, says St. Thomas, that prayer is necessary in order that God may know our necessities, but in order that we may know the necessity of having recourse to God to obtain the help necessary for our salvation, and may thus acknowledge him to be the author of all our good. As, therefore, it is God's law that we should provide ourselves with bread by sowing corn, and with wine by planting vines; so has he ordained that we should receive the graces necessary to salvation by means of prayer: "Ask, and it shall be given you; seek, and ye shall find." [Matt. 7: 7]We, in a word, are merely beggars, who have nothing but what God bestows on us as alms: "But I am a beggar and poor. [Ps. 39: 18] The Lord, says St. Augustine, desires and wills to pour forth his graces upon us, but will not give them except to him who prays. "God wishes to give, but only gives to him who asks." This is declared in the words, 'Seek and it shall be given to you.' Whence it follows, says St. Teresa, that he who seeks not, does not receive. As moisture is necessary for the life of plants, to prevent them from drying up, so, says St. Chrysostom, is prayer necessary for our salvation. Or, as he says in another place, prayer vivifies the soul, as the soul vivifies the body: "As the body without the soul cannot live, so the soul without prayer is dead and emits an offensive odor." He uses these words, because the man who omits to recommend himself to God, at once begins to be defiled with sins. Prayer is also called the food of the soul, because the body cannot be supported without food; nor can the soul, says St. Augustine, be kept alive without prayer: "As the flesh is nourished by food, so is man supported by prayers." All these comparisons used by the holy Fathers are intended by them to teach the absolute necessity of prayer for the salvation of everyone. www.catholictradition.org/Classics/prayer-1c.htm