The way of peace is through the wisdom taught in the Book of Proverbs, and through unity in the faith.
43 If you wish me to keep silence, cease from accusing me. Lay down your sword, and I will throw away my shield. To one thing only I cannot consent; that is, to spare the heretics, and not to vindicate my orthodoxy. If that is the cause of discord between us, I can submit to death, but not to silence. It would have been right to go through the whole of the Scriptures for answers to your ravings, and, like David playing on his harp, to take the divine words to calm your raging breast. But I will content myself with a few statements from a single book; I will oppose Wisdom to folly; for I hope if you despise the words of men you will not think lightly of the word of God. Listen, then, to that which Solomon the wise says about you and all who are addicted to evil speaking and contumely:
“Foolish men, while they desire injuries, become impious and hate wisdom. Devise not evil against your friend. Be not angry with a man without a cause. The impious exalt contumely. Remove from you the evil mouth, keep far from you the wicked lips, the eyes of him that speaks evil, the tongue of the unjust, the hands which shed the blood of the just, the heart that devises evil thoughts, and the feet which hasten to do evil. He that rests upon falsehood feeds the winds, and follows the flying birds. For he has left the ways of his own vineyard, and has made the wheels of his tillage to err. He walks through the dry and desert places, and with his hands he gathers barrenness. The mouth of the froward is near to destruction, and he who utters evil words is the chief of fools. Every simple man is a soul that is blessed; but a violent man is dishonourable. By the fault of his lips the sinner falls into a snare. All the ways of a fool are right in his own eyes. The fool shows his anger on that very day. Lying lips are an abomination to the Lord. He that keeps his lips guards his own soul; but he that is rash with his lips shall be a terror to himself. The evil man in his violence does evil things, and the fool spreads out his folly. Seek for wisdom among the evil and you shall not find it. The rash man shall eat of the fruit of his own ways. The wise man by taking heed avoids the evil; but the fool is confident, and joins himself to it. A long-suffering man is strong in his wisdom; the man of little mind is very unwise. He who oppresses the poor reproaches his Maker. The tongue of the wise knows good things, but the mouth of fools speaks evil. A quarrelsome man preferrs strife, and every one that lifts up his heart is unclean before God. Though hand join with hand unjustly, they shall not be unpunished. He that loves life must be sparing to his mouth. Insolence goes before bruising, and evil thoughts before a fall. He who closes his eyes speaks perverse things, and provokes all evil with his lips. The lips of a fool lead him into evil, and the foolhardy speech calls down death. The man of evil counsel shall suffer much loss. Better is a poor man who is just than a rich man that speaks lies. It is a glory to a man to turn away from evil words; but he that is foolish binds himself therewith. Love not detraction, lest you be rooted out. The bread of lying is sweet to a man, but afterwards his mouth shall be filled with gravel. He that gains treasures with a lying tongue follows vanity, and shall come into the snares of death. Say thou nought in the ear of a fool, lest haply the wise mock at your words. The bludgeon and the sword and the arrow are hurtful things; so is the man who bears false witness against his friend. As the birds and the sparrows fly away, so the curse shall be vain and shall not overtake him. Answer not an unwise man according to his lack of wisdom, lest you become like him; but answer a fool according to his folly, lest he appear to himself to be wise. He who lays wait for his friends when he is discovered says, I did it in sport. A faggot for the coals, and wood for the fire, and a man of evil words for the tumult of strife. If your enemy ask you anything, sparingly but with a loud voice, consent thou not to him, for there are seven degrees of wickedness in his heart. The stone is heavy, and the sand hard to be borne; but the anger of a fool is heavier than either; indignation is cruel, anger is sharp, and envy is impatient. The impious man speaks against the poor; and he that trusts in the audacity of his heart is most foolish. The unwise man puts forth all his anger, but the wise deals it out in parts. An evil son— his teeth are swords, and his grinders are as harrows, to consume the weak from off the earth, and the poor from among men.”
Such are the lessons in which I have been trained and therefore I was unwilling to return bite for bite, and to attack you by way of retaliation; and I thought it better to exorcise the madness of one who was raving, and to pour in the antidote of a single book into his poisoned breast. But I fear I shall have no success, and that I shall be compelled to sing the song of David, and to take his words for my only consolation:
“The wicked are estranged from the womb, they go astray even from the belly. They have spoken lies. Their madness is like the madness of the serpent; like the deaf adder which stops her ears, which will not hear the voice of the charmers, and of the magician wisely enchanting. God shall break their teeth in their mouth; the Lord shall break the great teeth of the lions. They shall come to nothing, like water that runs away. He bends his bow until they be brought low. Like wax that melts, they shall be carried away; the fire has fallen upon them and they have not seen the sun.”
And again:
“The righteous shall rejoice when he sees the vengeance upon the impious; he shall wash his hands in the blood of the sinner. And man shall say, Verily, there is a reward for the righteous; verily, there is a God that judges those that are on the earth.”
44. In the end of your letter you say: “I hope that you love peace.” To this I will answer in a few words: If you desire peace, lay down your arms. I can be at peace with one who shows kindness; I do not fear one who threatens me. Let us be at one in faith, and peace will follow immediately.
Source: Apology for himself against the Books of Rufinus (New Advent)