Here is a complete and exhaustive list of the Church’s teaching on the issue and topic of suicide. Starting with the Bible, I use all documents and works considered “ecclesiastical.”

Sacred Scripture

Exodus 20:13 – You shall not kill.

1 Samuel 31:4-5 – Then Saul said to his armor-bearer, “Draw your sword, and thrust me through with it, lest these uncircumcised come and thrust me through, and make sport of me.” But his armor-bearer would not; for he feared greatly. Therefore Saul took his own sword, and fell upon it. And when his armor-bearer saw that Saul was dead, he also fell upon his sword, and died with him.

2 Samual 17:23 – Then Saul said to his armor-bearer, “Draw your sword, and thrust me through with it, lest these uncircumcised come and thrust me through, and make sport of me.” But his armor-bearer would not; for he feared greatly. Therefore Saul took his own sword, and fell upon it. And when his armor-bearer saw that Saul was dead, he also fell upon his sword, and died with him.

Matthew 27:3-5 – When Judas, his betrayer, saw that he was condemned, he repented and brought back the thirty pieces of silver to the chief priests and the elders, saying, “I have sinned in betraying innocent blood.” They said, “What is that to us? See to it yourself.” And throwing down the pieces of silver in the temple, he departed; and he went and hanged himself.

The Catechism of the Catholic Church

2280. Everyone is responsible for his life before God who has given it to him. It is God who remains the sovereign Master of life. We are obliged to accept life gratefully and preserve it for his honor and the salvation of our souls. We are stewards, not owners, of the life God has entrusted to us. It is not ours to dispose of.

2281. Suicide contradicts the natural inclination of the human being to preserve and perpetuate his life. It is gravely contrary to the just love of self. It likewise offends love of neighbor because it unjustly breaks the ties of solidarity with family, nation, and other human societies to which we continue to have obligations. Suicide is contrary to love for the living God.

2282. If suicide is committed with the intention of setting an example, especially to the young, it also takes on the gravity of scandal. Voluntary co-operation in suicide is contrary to the moral law. Grave psychological disturbances, anguish, or grave fear of hardship, suffering, or torture can diminish the responsibility of the one committing suicide.

2283. We should not despair of the eternal salvation of persons who have taken their own lives. By ways known to him alone, God can provide the opportunity for salutary repentance. The Church prays for persons who have taken their own lives.

Papal Encyclicals

Evangelium Vitae, 65 – (on euthanasia) Certainly there is a moral obligation to care for oneself and to allow oneself to be cared for, but this duty must take account of concrete circumstances. It needs to be determined whether the means of treatment available are objectively proportionate to the prospects for improvement. To forego extraordinary or disproportionate means is not the equivalent of suicide or euthanasia; it rather expresses acceptance of the human condition in the face of death.

Papal Documents

Christifideles Laici, 38 – [entire section]

Ecclesia in America, 63 – This same concern must be shown to the elderly, who are often neglected and left to fend for themselves. They must be respected as persons; it is important to care for them and to help them in ways which will promote their rights and ensure their greatest possible physical and spiritual well-being. The elderly must be protected from situations or pressures which could drive them to suicide; in particular they must be helped nowadays to resist the temptation of assisted suicide and euthanasia.

Code of Canon Law

CIC 1041, 5 – The following are irregular for receiving orders:… a person who has mutilated himself or another gravely and maliciously or who has attempted suicide;

CCEO (Code of Canon Law for Eastern Churches) – same as above

Ecclesiastical Writers

Augustine, City of God.

17, CHAP. 17.—OF SUICIDE COMMITTED THROUGH FEAR OF PUNISHMENT OR DISHONOR
1. And consequently, even if some of these virgins killed themselves to avoid such disgrace, who that has any human feeling would refuse to forgive them? And as for those who would not put an end to their lives, lest they might seem to escape the crime of another by a sin of their own, he who lays this to their charge as a great wickedness is himself not guiltless of the fault of folly. For if it is not lawful to take the law into our own hands, and slay even a guilty person, whose death no public sentence has warranted, then certainly he who kills himself is a homicide, and so much the guiltier of his own death, as he was more innocent of that offence for which he doomed himself to die. Do we justly execrate the deed of Judas, and does truth itself pronounce that by hanging himself he rather aggravated than expiated the guilt of that most iniquitous betrayal, since, by despairing of God’s mercy in his sorrow that wrought death, he left to himself no place for a healing penitence? How much more ought he to abstain from laying violent hands on himself who has done nothing worthy of such a punishment! For Judas, when he killed himself, killed a wicked man; but he passed from this life chargeable not only with the death of Christ, but with his own: for though he killed himself on account of his crime, his killing himself was another crime. Why, then, should a man who has done no ill do ill to himself, and by killing himself kill the innocent to escape another’s guilty act, and perpetrate upon himself a sin of his own, that the sin of another may not be perpetrated on him?

20, CHAP. 20.—THAT CHRISTIANS HAVE NO AUTHORITY FOR COMMITTING SUICIDE IN ANY CIRCUMSTANCES WHATEVER
1. It is not without significance, that in no passage of the holy canonical books there can be found either divine precept or permission to take away our own life, whether for the sake of entering on the enjoyment of immortality, or of shunning, or ridding ourselves of anything whatever. Nay, the law, rightly interpreted, even prohibits suicide, where it says, “Thou shalt not kill.” This is proved especially by the omission of the words “thy neighbor,” which are inserted when false witness is forbidden: “Thou shalt not bear false witness against thy neighbor.” Nor yet should any one on this account suppose he has not broken this commandment if he has borne false witness only against himself. For the love of our neighbor is regulated by the love of ourselves, as it is written, “Thou shalt love thy neighbor as thyself.” If, then, he who makes false statements about himself is not less guilty of bearing false witness than if he had made them to the injury of his neighbor; although in the commandment prohibiting false witness only his neighbor is mentioned, and persons taking no pains to understand it might suppose that a man was allowed to be a false witness to his own hurt; how much greater reason have we to understand that a man may not kill himself, since in the commandment,” Thou shalt not kill,” there is no limitation added nor any exception made in favor of any one, and least of all in favor of him on whom the command is laid! And so some attempt to extend this command even to beasts and cattle, as if it forbade us to take life from any creature. But if so, why not extend it also to the plants, and all that is rooted in and nourished by the earth? For though this class of creatures have no sensation, yet they also are said to live, and consequently they can die; and therefore, if violence be done them, can be killed. So, too, the apostle, when speaking of the seeds of such things as these, says, “That which thou sowest is not quickened except it die;” and in the Psalm it is said, “He killed their vines with hail.” Must we therefore reckon it a breaking of this commandment, “Thou shalt not kill,” to pull a flower? Are we thus insanely to countenance the foolish error of the Manichæans? Putting aside, then, these ravings, if, when we say, Thou shalt not kill, we do not understand this of the plants, since they have no sensation, nor of the irrational animals that fly, swim, walk, or creep, since they are dissociated from us by their want of reason, and are therefore by the just appointment of the Creator subjected to us to kill or keep alive for our own uses; if so, then it remains that we understand that commandment simply of man. The commandment is, “Thou shall not kill man;” therefore neither another nor yourself, for he who kills himself still kills nothing else than man.

22, CHAP. 22.—THAT SUICIDE CAN NEVER BE PROMPTED BY MAGNANIMITY
1. But they who have laid violent hands on themselves are perhaps to be admired for their greatness of soul, though they cannot be applauded for the soundness of their judgment. However, if you look at the matter more closely, you will scarcely call it greatness of soul, which prompts a man to kill himself rather than bear up against some hardships of fortune, or sins in which he is not implicated. Is it not rather proof of a feeble mind, to be unable to bear either the pains of bodily servitude or the foolish opinion of the vulgar? And is not that to be pronounced the greater mind, which rather faces than flees the ills of life, and which, in comparison of the light and purity of conscience, holds in small esteem the judgment of men, and specially of the vulgar, which is frequently involved in a mist of error? And, therefore, if suicide is to be esteemed a magnanimous act, none can take higher rank for magnanimity than that Cleombrotus, who (as the story goes), when he had read Plato’s book in which he treats of the immortality of the soul, threw himself from a wall, and so passed from this life to that which he believed to be better. For he was not hard pressed by calamity, nor by any accusation, false or true, which he could not very well have lived down; there was, in short, no motive but only magnanimity urging him to seek death, and break away from the sweet detention of this life. And yet that this was a magnanimous rather than a justifiable action, Plato himself, whom he had read, would have told him; for he would certainly have been forward to commit, or at least to recommend suicide, had not the same bright intellect which saw that the soul was immortal, discerned also that to seek immortality by suicide was to be prohibited rather than encouraged.
2. Again, it is said many have killed themselves to prevent an enemy doing so. But we are not inquiring whether it has been done, but whether it ought to have been done. Sound judgment is to be preferred even to examples, and indeed examples harmonize with the voice of reason; but not all examples, but those only which are distinguished by their piety, and are proportionately worthy of imitation. For suicide we cannot cite the example of patriarchs, prophets, or apostles; though our Lord Jesus Christ, when He admonished them to flee from city to city if they were persecuted, might very well have taken that occasion to advise them to lay violent hands on themselves, and so escape their persecutors. But seeing He did not do this, nor proposed this mode of departing this life, though He were addressing His own friends for whom He had promised to prepare everlasting mansions, it is obvious that such examples as are produced from the “nations that forget God,” give no warrant of imitation to the worshippers of the one true God.

23, CHAP. 23.—WHAT WE ARE TO THINK OF THE EXAMPLE OF CATO, WHO SLEW HIMSELF BECAUSE UNABLE TO ENDURE CÆSAR’S VICTORY
1. Besides Lucretia, of whom enough has already been said, our advocates of suicide have some difficulty in finding any other prescriptive example, unless it be that of Cato, who killed himself at Utica. His example is appealed to, not because he was the only man who did so, but because he was so esteemed as a learned and excellent man, that it could plausibly be maintained that what he did was and is a good thing to do. But of this action of his, what can I say but that his own friends, enlightened men as he, prudently dissuaded him, and therefore judged his act to be that of a feeble rather than a strong spirit, and dictated not by honorable feeling forestalling shame, but by weakness shrinking from hardships? Indeed, Cato condemns himself by the advice he gave to his dearly loved son. For if it was a disgrace to live under Cæsar’s rule, why did the father urge the son to this disgrace, by encouraging him to trust absolutely to Cæsar’s generosity? Why did he not persuade him to die along with himself? If Torquatus was applauded for putting his son to death, when contrary to orders he had engaged, and engaged successfully, with the enemy, why did conquered Cato spare his conquered son, though he did not spare himself? Was it more disgraceful to be a victor contrary to orders, than to submit to a victor contrary to the received ideas of honor? Cato, then, cannot have deemed it to be shameful to live under Cæsar’s rule; for had he done so, the father’s sword would have delivered his son from this disgrace. The truth is, that his son, whom he both hoped and desired would be spared by Cæsar, was not more loved by him than Cæsar was envied the glory of pardoning him.

Eusebuis, The Church History, Book II, Chapter VII – Pilate’s Suicide, It is worthy of note that Pilate himself, who was governor in the time of our Saviour, is reported to have fallen into such misfortunes under Caius, whose times we are recording, that he was forced to become his own murderer and executioner; and thus divine vengeance, as it seems, was not long in overtaking him. This is stated by those Greek historians who have recorded the Olympiads, together with the respective events which have taken place in each period.