Christ teaches us to love our enemies and to forgive them. This is the teaching of the New Testament.
"But I say to you, love your enemies, bless those who curse you, do good to those who hate you, and pray for those who spitefully use you and persecute you" (Matthew 5:44). "For if you forgive men their trespasses, your heavenly Father will also forgive you. But if you do not forgive men their trespasses, neither will your Father forgive your trespasses" (Matthew 6:14). "Then Jesus said, 'Father, forgive them, for they do not know what they do' " (Luke 23:34).
"Bless those who persecute you; bless and do not curse" (Romans 12:14). "But no man can tame the tongue. It is an unruly evil, full of deadly poison. With it we bless our God and Father, and with it we curse men, who have been made in the similitude of God. Out of the same mouth proceed blessing and cursing. My brethren, these things ought not to be so. Does a spring send forth fresh water and bitter from the same opening? Can a fig tree, my brethren, bear olives, or a grapevine bear figs? Thus no spring yields both salt water and fresh" (James 3:8-12).
"He who does not love does not know God, for God is love" (1 John 4:8). "God is love, and he who abides in love abides in God, and God in him" (1 John 4:16). "For when we were still without strength, in due time Christ died for the ungodly. For scarcely for a righteous man will one die; yet perhaps for a good man someone would even dare to die. But God demonstrates His own love toward us, in that while we were still sinners, Christ died for us" (Romans 5:6-8). "For God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life" (John 3:16). "And they stoned Stephen as he was calling on God and saying, 'Lord Jesus, receive my spirit.' Then he knelt down and cried out with a loud voice, 'Lord, do not charge them with this sin.' And when he had said this, he fell asleep" (Acts 7:59-60).
Yet many of the Psalms of David and other Psalm writers pray for God's vengeance against the wicked.
Here are some examples:
"For there is no faithfulness in their mouth; Their inward part is destruction; Their throat is an open tomb; They flatter with their tongue. Pronounce them guilty, O God! Let them fall by their own counsels; Cast them out in the multitude of their transgressions,
For they have rebelled against You" (Psalm 5:9-10). "Let those be put to shame and brought to dishonor Who seek after my life; Let those be turned back and brought to confusion Who plot my hurt. Let them be like chaff before the wind, And let the angel of the Lord chase them. Let their way be dark and slippery, And let the angel of the Lord pursue them. For without cause they have hidden their net for me in a pit, Which they have dug without cause for my life. Let destruction come upon him unexpectedly, And let his net that he has hidden catch himself; Into that very destruction let him fall" (Psalm 35:4-8).
"Let them be ashamed and brought to mutual confusion Who rejoice at my hurt; Let them be clothed with shame and dishonor Who exalt themselves against me" (Psalm 35:26). "Let death seize them; Let them go down alive into hell, For wickedness is in their dwellings and among them" (Psalm 55:15). "Let their table become a snare before them, And their well-being a trap. Let their eyes be darkened, so that they do not see; And make their loins shake continually. Pour out Your indignation upon them, And let Your wrathful anger take hold of them. Let their dwelling place be desolate; Let no one live in their tents. For they persecute the ones You have struck, And talk of the grief of those You have wounded. Add iniquity to their iniquity, And let them not come into Your righteousness. Let them be blotted out of the book of the living, And not be written with the righteous" (Psalm 69:22-28).
"Set a wicked man over him, And let an accuser stand at his right hand. When he is judged, let him be found guilty, And let his prayer become sin. Let his days be few, And let another take his office. Let his children be fatherless, And his wife a widow. Let his children continually be vagabonds, and beg; Let them seek their bread also from their desolate places. Let the creditor seize all that he has, And let strangers plunder his labor. Let there be none to extend mercy to him, Nor let there be any to favor his fatherless children. Let his posterity be cut off, And in the generation following let their name be blotted out. Let the iniquity of his fathers be remembered before the Lord, And let not the sin of his mother be blotted out. Let them be continually before the Lord, That He may cut off the memory of them from the earth; Because he did not remember to show mercy, But persecuted the poor and needy man, That he might even slay the broken in heart. As he loved cursing, so let it come to him; As he did not delight in blessing, so let it be far from him. As he clothed himself with cursing as with his garment, So let it enter his body like water, And like oil into his bones. Let it be to him like the garment which covers him, And for a belt with which he girds himself continually. Let this be the Lord’s reward to my accusers, And to those who speak evil against my person" (Psalm 109:6-20).
"By the rivers of Babylon, There we sat down, yea, we wept When we remembered Zion. We hung our harps Upon the willows in the midst of it. For there those who carried us away captive asked of us a song, And those who plundered us requested mirth, Saying, 'Sing us one of the songs of Zion!'...Remember, O Lord, against the sons of Edom The day of Jerusalem, Who said, 'Raze it, raze it, To its very foundation!' O daughter of Babylon, who are to be destroyed, Happy the one who repays you as you have served us! Happy the one who takes and dashes Your little ones against the rock!" (Psalm 137:1-3, 7-9).
"Do I not hate them, O Lord, who hate You? And do I not loathe those who rise up against You? I hate them with perfect hatred; I count them my enemies" (Psalm 139:21-22).
Also see Psalms 28:4-5, 40:14-15, 58:6-8, 59:5, 12-13, 70:2-3, 71:12-13, 83:9-18, 101:3-8, 104:35, 140:9-11, 141:10, 143:12, 149:5-9.
We know that the Old Testament is as much God's word as the New Testament. Christ, in referring to an Old Testament scripture, said scripture cannot be broken (John 10:34-35). Paul wrote, "All Scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness" (2 Timothy 3:16).
How can we reconcile the harshness of some of the Psalms with the mercy taught in the New Testament?
Both are true and right teachings, and both reflect the mind of God. David is called a man after God's heart (1 Samuel 13:13-14, Acts 13:22).
David's prayers for vengeance against the wicked are a true reflection of God's thinking toward sinners who never repent and towards sin itself.
People in the world, in mainstream religion, and some in the Church, say that God hates sin but loves the sinner. This is true, as long as there is the possibility that the sinner will repent. God loves the sinner in the sense that He desires that he repents (Ezekiel 33:11, 2 Peter 3:9).
BUT, if the sinner permanently chooses the way of Satan, the way of sin, if he refuses to repent, then the severe nature of God applies to that person (God has a severe side - see Romans 11:22), and God will hate the sinner who refuses to put away his sin with a permanent hatred, and God will, in wrath and fury, destroy the sinner in the lake of fire forever.
God is both loving and vengeful. His love is towards those who will repent and choose His way of life. His vengeance is towards those who refuse to repent.
Vengeance is not, in principle, always wrong, but it is wrong for man to take vengeance because it does not belong to us. "For we know Him who said, 'Vengeance is Mine, I will repay,' says the Lord. And again, 'The Lord will judge His people.' It is a fearful thing to fall into the hands of the living God" (Hebrews 10:30-31). See also Deuteronomy 32:35, Psalm 94:1, Romans 12:18-21, 1 Thessalonians 4:6. Vengeance is the result of God's judgment against sinners, and only God has the right to exercise that kind of judgment.
God teaches us lessons in the Bible in a certain logical order. The lessons of the Old Testament come first and prepare us to understand the New Testament.
In Worldwide, when Mr. Tkach began to change doctrine to become more like mainstream Protestant doctrine, they used to say that the Old Testament can only be understood in light of the New Testament, implying we should study the New Testament first to prepare us to understand the Old Testament. But that is backwards. God inspired the Old Testament to be written first, then the New Testament. Studying the Old Testament first prepares us and helps us to understand the New Testament. That is the order in which God revealed His truth. The New Testament was written in the context of the knowledge of the Old Testament, and it can only be rightly understood in the context of what we have learned in the Old Testament.
The Old Testament teaches God's wrath and punishment for sin, and it also teaches God's mercy. The New Testament also teaches both God's wrath and God's mercy. Yet the emphasis is different between the two halves of the Bible. In the Old Testament, God teaches His wrath, vengeance, and punishment against the wicked with greater emphasis, while the New Testament places greater emphasis on God's merciful side. This is fitting, because the sacrifice of Christ is only fully revealed in the New Testament, and it is through that sacrifice that God's mercy and love is most fully expressed. "For the law was given through Moses, but grace and truth came through Jesus Christ" (John 1:17).
David had God's Holy Spirit (Psalm 51:11). David was therefore living under the terms of the new covenant as well as the old. He understood what he needed to know about the sacrifice of Christ and the resurrection to eternal life. He understood God's mercy. Yet God inspired David to write many of the Psalms emphasizing God's wrath towards sin and toward sinners because it was God's time to place emphasis on that aspect of God's judgment and thinking.
God hates sin. And God also, in a sense, hates sinners who do not repent. He hates them enough to inflict a torturous death upon them and destroy them forever. This aspect of God's thinking is what the Psalms teach.
God loves sinners in the sense that He desires them to repent. "Say to them: 'As I live,' says the Lord God, 'I have no pleasure in the death of the wicked, but that the wicked turn from his way and live. Turn, turn from your evil ways! For why should you die, O house of Israel?' " (Ezekiel 33:11). "The Lord is not slack concerning His promise, as some count slackness, but is longsuffering toward us, not willing that any should perish but that all should come to repentance" (2 Peter 3:9). But once that option is rejected permanently, when a sinner has the option to repent but finally, in the end, rejects that opportunity to repent and turn from sin, then God's hatred is not just towards the sin but towards the sinner who refuses to part with his sin. The sinner and the sin become one in God's sight, and He hates them, both. Either that, or I don't know what the word "hate" means.
Yet, even as God shows His wrath towards the sin and the sinner He hates by casting them into the lake of fire, His wrath is tempered by mercy in that the sinner's torment does not continue forever but ends as the sinner is destroyed and ceases to exist forever.
What about the sinner who still has time to repent in the future, but has not done so yet? This, in principle, applies to the majority of the world which has not been called to salvation yet.
God's wrath, His vengeance, hangs over their heads. They are still in their sins (1 Corinthians 15:17). They are children of wrath (Ephesians 2:3). They have not yet passed from death to life (John 5:24, 1 John 3:14).
God's will is that they repent, and in that sense, God loves them, conditional on that future repentance. But until they actually repent, God's wrath hangs over their heads, proportional to their sin, the greater the sin, the greater God's wrath that hangs over them. God may from time to time show mercy by answering prayers of the sinner, to show His mercy, to teach lessons, to encourage the future repentance He desires. But God's love and mercy are not fully given till actual repentance occurs.
And because God is a true witness, He sometimes demonstrates the ultimate consequences of unrepentant sin by punishing the wicked very harshly in this life. When He does that, He is giving them a taste, enough to let them know that they are in trouble if they keep going the way they do.
The prayers for vengeance against the wicked in the Psalms are a true reflection of the mind of God towards sinners who do not repent.
God's mercy is towards those who repent and turn from their sin and learn to believe and obey God as a way of life.