According to St. John Henry Newman himself, these are his most important works.
Lectures on Justification
13 Brilliant Lectures on Justification, synthesizing the Catholic and Protestant theories.
Apologia pro vita sua
Newman's spiritual autobiography. Regarded as a spiritual classic.
Development of Christian Doctrine
“It remains the classic text for the theology of the development of doctrine, a branch of theology which has become especially important in the ecumenical era.” ~ Ian Ker
Idea of a University
Newman's lectures on the nature of a University and education and what it ought to be.
Grammar of Assent
This classic of Christian apologetics seeks to persuade the skeptic that there are good reasons to believe in God even though it is impossible to understand the deity fully.
"As God rules the will, yet the will is free,—as He rules the course of the world, yet men conduct it,—so He has inspired the Bible, yet men have written it"
"All Scripture has its difficulties; but let us not, on account of what is difficult, neglect what is clear."
"Who shall give method to what is infinitely complex, and measure to the unfathomable?"
On Perplexing Passages
"And here I would make a remark: that when a passage of Scripture, descriptive of God’s dealings with man, is obscure or perplexing, it is as well to ask ourselves whether this may not be owing to some insensibility, in ourselves or in our age, to certain peculiarities of the Divine law or government therein involved. Thus, to those who do not understand the nature and history of religious truth, our Lord’s assertion about sending a sword on earth is an obscurity. To those who consider sin a light evil, the doctrine of eternal punishment is a difficulty. In like manner the history of the flood, of the call of Abraham, of the plagues of Egypt, of the wandering in the desert, of the judgment on Korah, Dathan, and Abiram, and a multitude of other occurrences, may be insuperable difficulties, except to certain states and tempers of mind, to which, on the contrary, they will seem quite natural and obvious."
On Difficulties in Scripture
" All Scripture has its difficulties; but let us not, on account of what is difficult, neglect what is clear. Let us be sure there are many things said in Scripture most clearly, many things which any one, under God’s grace, might gain for himself from Scripture, which we do not gain from it; many truths, which all men, if they carefully thought over the sacred text, would one and all agree in finding there. Perchance, if we had learnt from it what we can learn by our own private study, we should be more patient of learning from others those further truths which, though in Scripture, we cannot learn from it by ourselves."
"4:2 “And when he had fasted forty days and forty nights, he was afterward hungered.”
Next I observe, that our Savior’s fast was but introductory to His temptation. He went into the wilderness to be tempted of the devil, but before He was tempted He fasted. Nor, as is worth notice, was this a mere preparation for the conflict, but it was the cause of the conflict in good measure. Instead of its simply arming Him against temptation, it is plain, that in the first instance, His retirement and abstinence exposed Him to it. Fasting was the primary occasion of it. “When He had fasted forty days and forty nights, He was afterwards an hungered;” and then the tempter came, bidding Him turn the stones into bread. Satan made use of His fast against Himself."
"No one has access to the Almighty as His Mother has; none has merit such as hers. Her Son will deny her nothing that she asks; and herein lies her power. While she defends the Church, neither height nor depth, neither men nor evil spirits, neither great monarchs, nor craft of man, nor popular violence, can avail to harm us; for human life is short, but Mary reigns above, a Queen forever."
"Have you any intention to deny that Mary was as fully endowed as Eve? Is it any violent inference that she, who was to cooperate in the redemption of the world, was at least not less endowed with power from on high than she who, given as a helpmate to her husband did in the event but cooperate with him for its ruin?"
"If Mary had a meritorious share in bringing about our redemption; if her maternity was gained by her faith and obedience; if her divine Son was subject to her; and if she stood by the cross with a mother’s heart and drank in to the full those sufferings which it was her portion to gaze upon, it is impossible that we should not associate these characteristics of her life on earth with her present state of blessedness. And this surely she anticipated when she said in her hymn that all “generations should call me blessed."
"In the eternal enmity which exists between the woman and the serpent, while the serpent’s strength lies in being the Tempter, the weapon of the Second Eve and Mother of God is prayer."
"Men sometimes wonder that we call her Mother of life, of mercy, of salvation; what are all these titles compared to that one name, Mother of God?"
"Catholics who have honored the Mother still worship the Son, while Protestants, who now have ceased to confess the Son, began then by scoffing at the Mother."
"Make me preach Thee without preaching — not by words, but by my example and by the catching force, the sympathetic influence, of what I do — by my visible resemblance to Thy saints, and the evident fulness of the love which my heart bears to Thee."
"O mighty God, strengthen me with Thy strength, console me with Thy everlasting peace, soothe me with the beauty of Thy countenance; enlighten me with Thy uncreated brightness; purify me with the fragrance of Thy ineffable holiness. Bathe me in Thyself, and give me to drink, as far as mortal man may ask, of the rivers of grace which flow from the Father and the Son, the grace of Thy consubstantial, co-eternal Love."
"Stay with me, and then I shall begin to shine as Thou shinest: so to shine as to be a light to others. The light, O Jesus, will be all from Thee. None of it will be mine. No merit to me. It will be Thou who shinest through me upon others"
"For us, my dear Brethren, whose duties lie in this seat of learning and science, may we never be carried away by any undue fondness for any human branch of study, so as to be forgetful that our true wisdom, and nobility, and strength, consist in the knowledge of Almighty God. Nature and man are our studies, but God is higher than all. It is easy to lose Him in His works. It is easy to become over-attached to our own pursuit, to substitute it for religion, and to make it the fuel of pride."
"When we love a person, we cannot but wish he should love us; but he cannot love us, without also feeling respect and esteem towards us. And as to the question, from whom we should desire praise, and how far, we have this simple rule —from all who stand to us in Christ’s place. Christ Himself is our great Judge; from Him we must supremely seek praise; and as far as men are in His place, so far may we seek it from men. We may desire the praise of our parents and superiors, and the praise of good men — in a word, all whom we have a value for; but the desire of indiscriminate praise, the praise of those for whom we have no respect or regard, this is the mischief."
"(Many men) have a number of good qualities, and are in a certain sense and up to certain point religious; but they do not watch. Their notion of religion is briefly this: loving God indeed, but loving this world too; not only doing their duty, but finding their chief and highest good , in that state of life to which it has pleased God to call them, resting in it, taking it as their portion. They serve God, and they seek Him; but they look on the present world as if it were eternal."