So where do the rules come from? Well, the rules of right behavior tend to come from two sources. The first is from religion, and is concerned with holiness. All over the world, religions of various kinds have taught that God or the gods are special, and must be approached under special conditions. We have to be purified to meet with divinity. And when we are in the presence of divinity, we have to watch ourselves lest we give offense. “Moses, Moses, put off thy shoes from off thy feet, for the place whereon thou standest is holy ground.” G.K. Chesterton said that the first moral principle to be discovered was not, “I must not hit my brother,” but rather “I must not hit my brother in the holy place.” Most religions have fairly complicated rules about ritual purity, about special times and places, about how to pray, and so on.
Holiness/purity/morality, however was in ancient times not considered the same sort of thing as ethics. That was the realm of philosophy, not religion. Philosophy considered the way to live a good life in general. And “ethics” comes from ethos, “a people.” Each people had a way of living, a set of customs; ethics was thus the way of living together with other people. Here is where the idea that how we treated our neighbors mattered. Philosophers often commented upon custom, and took to pronouncing a higher sort of ethics based upon a perception of what kind of behavior should be natural to all people, not just a people. Different philosophies worked up slightly different sets of ethical rules, just as different religions had different notions of moral purity.
The two kinds of right behavior came together for the first time in the God of the Bible, for he was the first ethical God worshiped in human history. In other words, not only did he care about how you acted on his turf; he cared about how you acted when you were at home, at work, even by yourself. And he was not only holy, but righteous. “Why do you call me good?” asked Jesus. “No one is good but God alone.” To be good, therefore, meant trying to be like God: holy toward him and righteous toward each other.
The Old Testament contains a great number of commandments (613 of them, to be precise). Some are concerned with ritual purity, others with how we live our ordinary lives. After the resurrection of Jesus, the new Christian Church agreed that new converts from outside Judaism would not have to keep the ritual laws of the Old Testament in order to become Christians. We are still called upon to be holy, but we have far fewer expectations of a ritual sort. Our set of rules is therefore much simpler – but also more demanding. We are always in the presence of God, and we are to act like it. We can never just do as we like; other people – and God – have to be taken into account. We fail a lot, it should be said, but we keep trying.
And Jesus said that God can make us able to succeed. This is his working in us, not our own strength and goodness. But this is our goal, to love God with all our heart, soul, mind, and strength; and also, to love our neighbor as ourself. And so this is what we recommend to others. This is what works, if you will. This is what keeps us from falling off the point we are standing on and going smash on the rocks below. This is what keeps society from falling apart into a war of all against all.
Since we get this not just from custom or whatever philosophy seems to commend itself to us, but from God himself, we are not at liberty to amend it as we please. And experience shows us that even if God had not personally commanded this or that, yet when we try to carve out exceptions to the rules to please ourselves, we overbalance and slip off the point we are trying to stay on. So now, even when we don’t completely understand why a particular rule is given us, we continue to struggle to understand, and to continue to obey it, since experience has shown us that God is wiser than we.