Did God who calls upon His people to kill in the Old Testament, suddenly become merciful since, through Jesus, He calls upon His people to love their enemies?
Answer: The biblical narrative presents an evolution over time regarding the question whether it is legitimate to kill one’s neighbour, as well as the religious and ethical significance of war and military force: Here God enables His people to increasingly and clearly discern the contours of His will, which reaches perfection in Jesus life and teaching. We present this evolution in two strands.
1. The prohibition in the fifth commandment against murder and killing and Jesus commandment to love
The Old Testament teachings regarding the value and dignity of human life are succinctly formulated in the fifth Commandment of the Decalogue: You shall not murder (Ex 20:13; Deut 5:17). The reason why the Bible talks of murder instead of killing is because the corresponding Hebrew word does not mean killing in the sense of killing as such, but in the sense of unlawful killing. It is primarily aimed at murder but also includes manslaughter.
The fifth commandment reflects the conviction in Israel that life is valuable and sacrosanct. This applies particularly to human life since the human being is an image of God. This is the source of their worth and dignity. No one is allowed to arbitrarily dispose of human life. Whoever violates human life will be severely punished. Whoever sheds the blood of a human, by a human shall that person’s blood be shed, for in his own image God made humankind (Gen 9:6). The deliberate annihilation of a fellow human beings life will be regarded as a sin crying out to me from the ground (Gen 4:10). Whoever murdered was condemned to death and the murderer could not buy his own freedom (cf. Num 35:25). Precisely this heavy sanction by the community reveals its respect for the God of life…
The positive purpose of the fifth Commandment is humankind’s Yes to its fellow human beings, which has its foundation in humankind’s Yes to God and in God’s Yes to humankind.
According to the Old Testament, the Yes to Yahweh is only then a fully valid Yes when it is directed towards God and humankind. Yes to God and Yes to humankind form the foundation of what the Bible calls love. That is why immediately after the proclamation of the Decalogue (Deut 5), Deuteronomy contains the fundamental demand of the Yes to God in the expression: Hear, O Israel. The Lord is our God, the Lord alone. You shall love the Lord your God with all your heart and with all your soul, and with all your might (Deut 6:4). The commandment to love God also addresses love of one’s neighbour…The explicit expression is: You shall love your neighbour as yourself (Lev 19:18). That also applies to aliens (cf Lev 19:33ff). This revelation of divine will was summarised by the prophet Micah in this way: He has told you, O mortal, what is good; and what does the Lord require of you but to do justice, and to love kindness, and to walk humbly with your God (Mic 6:8).
What is proclaimed in the Old Testament commandments to love God and one’s neighbour (Deut 6:4ff; Lev 19:18) as the revelation of divine will and what the prophets refer to in concrete social actions, is impressively confirmed and outdone in Jesus and His message. He, who is the the justice of God and who brings the message of Gods justice as loving mercy commands, as words of the prophet Hosea (6:6) say: I desire mercy, not sacrifice (Mt 9:13; 12:7)…. Jesus broadens the general framework of the prohibition against killing. Not just physical manslaughter but even anger and evil words achieve the offence of killing: You have heard that it was said to those of ancient times, 'You shall not murder'; and 'whoever murders shall be liable to judgment.' But I say to you that if you are angry with a brother or sister, you will be liable to judgment (Mt 5:21). The final reason for the commandment not to kill, not to be angry, not to hate is to be a commandment to love on which all other laws depend (cf Mt 22:37–40). Jesus expands this commandment to love to include all people, also ones enemies (Mt 5:44). He commands not only an inner disposition of benevolence, but also to do good in concrete actions. Jesus Himself expresses love of neighbour in His particular devotion to the poor, the weak, the disadvantaged and the sick. According to Jesus judgment of the nations (Mt 25), the decision over salvation or doom depends on whether we have actually put into practice this love in works of charity. Jesus said that the charity shown to others was the charity shown to Him.
Just as you did it to one of the least of these who are members of my family, you did it to me… Just as you did not do it to one of the least of these, you did not do it to me. (Mt 25:40.45).
The commandment acknowledged by all people “You shall not kill!” changes under the influence of the Christian proclamation and the modern orientation towards humankind into: Preserve life This positive orientation affects people in the changed world that we now live in with an urgency that our forebears could not have perceived in earlier times. Scientific, technical, economic and political opportunities have made more apparent than was ever possible before not only the grandeur of human life, but also the limits and threats to human life. Human responsibility for life covers all the aspects of ones own life, the life of others from beginning to end, on peaceful co-existence in society, between nations, peoples, and in preserving creation. Thus the fifth commandment is simultaneously an individual and a social commandment. (Abbreviated and slightly modified from: Leben aus dem Glauben, Katholischer Erwachsenenkatechismus (Catholic Adult Catechism), Vol. 2, pp. 270-75).
2. War as a topic in the Bible and Jesus commandment to love
Even if today’s research into the Old Testament seldom accepts that ancient Israel knew holy wars in the way that wars were carried out by the city alliance in aid of the sanctuary of Delphi, ancient Israel evidently still regarded the God of the Israelites as a god of war, as the Lord of Hosts, the God of the armies of Israel (1 Sam 17:45). Israel’s early history is still interpreted as a history of military self-determination under Yahweh’s help. Yahweh’s and Israel’s interests largely coincide and Israel’s wars are Yahweh’s wars. The annihilation of the enemy is considered as an act by Yahweh Himself (Ex 15:21). However, following the consolidation of the Davidian empire, Israel increasingly called into question its early identification of Gods will and military self-determination, and the military ascendancy of the people. Israel is increasingly pulled into the power-political and military conflicts around it and finally falls victim with its captivity in Babylon. Particularly the prophets call for unshrinking silence in the midst of war (Isa 7:4.9; 30:15) and proclaim that Yahweh Himself will break Israel’s weapons (Hos 1:5) and will bring about an end-of-time peace when the people shall beat their swords into ploughshares (Isa 2:4; Mic 4:3). There are also expectations of an end-of-time military act by Yahweh, which will put an end to worldly power (Ez 30). Israel’s military disposition was also very dominant during the time of the Maccabees. However, Rabbinical Jewry emphasised the primacy of peace, for peace is the will of God and is Gods name. However, in the present, following the founding of the State of Israel, this has seldom led to a pacific willingness to compromise.….
Early Christianity lived in a world of major political conflicts and uprisings. Conflicts with the Roman occupiers urged insurrection and a fight for freedom, but from the beginning Jesus distanced Himself from every political-Messianic picture (Mt 4:10; 26:52; Mk 10:42ff; Jn 18:36). In linking the title of the Son of Man with the image and form of the suffering servant of God, the early community’s proclamation rejected the political Messiah. Alongside Jesus instructions to love one’s neighbour and to renounce all violence, as passed down in the Sermon on the Mount (Mt 5:38ff), is of course also the demand to basically acknowledge political violence (Rom 13:1 ff). This tension characterise Christianity’s relationship to war and peace up to the present time…
In recent times in view of the production and stationing of an ever-growing number of more powerful weapons of mass destruction the Churches have withdrawn the ethical legitimacy of their use. Even if it cannot be said that the traditions of a just war have now given way to a model of just peace, the conciliar process for Justice, Peace and the Preservation of Creation clearly indicates this direction (from Wolfgang Lienemann, art. Krieg in: Evangelisches Kirchenlexikon [Göttingen, 1989], Vol. 2, pp 1477-1481).