From the Catholic Catechism:
I. RESPECT FOR THE HUMAN PERSON
1929 Social justice can be obtained only in respecting the transcendent dignity of man. The person represents the ultimate end of society, which is ordered to him:
What is at stake is the dignity of the human person, whose defense and promotion have been entrusted to us by the Creator, and to whom the men and women at every moment of history are strictly and responsibly in debt.
1930 Respect for the human person entails respect for the rights that flow from his dignity as a creature. These rights are prior to society and must be recognized by it. They are the basis of the moral legitimacy of every authority: by flouting them, or refusing to recognize them in its positive legislation, a society undermines its own moral legitimacy. If it does not respect them, authority can rely only on force or violence to obtain obedience from its subjects. It is the Church’s role to remind men of good will of these rights and to distinguish them from unwarranted or false claims.
1931 Respect for the human person proceeds by way of respect for the principle that “everyone should look upon his neighbor (without any exception) as ‘another self,’ above all bearing in mind his life and the means necessary for living it with dignity.” No legislation could by itself do away with the fears, prejudices, and attitudes of pride and selfishness which obstruct the establishment of truly fraternal societies. Such behavior will cease only through the charity that finds in every man a “neighbor,” a brother.
1932 The duty of making oneself a neighbor to others and actively serving them becomes even more urgent when it involves the disadvantaged, in whatever area this may be. “As you did it to one of the least of these my brethren, you did it to me.”
1933 This same duty extends to those who think or act differently from us. The teaching of Christ goes so far as to require the forgiveness of offenses. He extends the commandment of love, which is that of the New Law, to all enemies. Liberation in the spirit of the Gospel is incompatible with hatred of one’s enemy as a person, but not with hatred of the evil that he does as an enemy. [footnotes]
Abortion, Euthanasia, War:
2318 “In [God’s] hand is the life of every living thing and the breath of all mankind” (Job 12:10).
2319 Every human life, from the moment of conception until death, is sacred because the human person has been willed for its own sake in the image and likeness of the living and holy God.
2320 The murder of a human being is gravely contrary to the dignity of the person and the holiness of the Creator.
2321 The prohibition of murder does not abrogate the right to render an unjust aggressor unable to inflict harm. Legitimate defense is a grave duty for whoever is responsible for the lives of others or the common good.
2322 From its conception, the child has the right to life. Direct abortion, that is, abortion willed as an end or as a means, is a “criminal” practice (GS 27 § 3), gravely contrary to the moral law. The Church imposes the canonical penalty of excommunication for this crime against human life.
2323 Because it should be treated as a person from conception, the embryo must be defended in its integrity, cared for, and healed like every other human being.
2324 Intentional euthanasia, whatever its forms or motives, is murder. It is gravely contrary to the dignity of the human person and to the respect due to the living God, his Creator.
2325 Suicide is seriously contrary to justice, hope, and charity. It is forbidden by the fifth commandment.
2326 Scandal is a grave offense when by deed or omission it deliberately leads others to sin gravely.
2327 Because of the evils and injustices that all war brings with it, we must do everything reasonably possible to avoid it. The Church prays: “From famine, pestilence, and war, O Lord, deliver us.”
2328 The Church and human reason assert the permanent validity of the moral law during armed conflicts. Practices deliberately contrary to the law of nations and to its universal principles are crimes.
2329 “The arms race is one of the greatest curses on the human race and the harm it inflicts on the poor is more than can be endured” (GS 81 § 3).
2330 “Blessed are the peacemakers, for they shall be called sons of God” (Mt 5:9).