This short essay is not intended to be a scientific analysis, nor is it complete.
Its purpose is to summarise the topic and provide examples of behaviour.
The Natural Law is imposed on men to define behaviour within the limits God wishes us to have. This law has been given to us so that we can know how God intends us to lead our lives. That is, we are given certain limits on our behaviour, and under normal circumstances men know what those limits are. The natural law is known to and applies to all people. Man is capable of acquiring knowledge of the natural law through reason.
1 Preserving life
We know that we must preserve life. We cannot take our own life, or the lives of others. We must take care of our health. Thus we know that the use of drugs is wrong, as is an excess of alcohol.
We are given an appetite for food, and some foods are more appetising than others. Food is essential for life, but to simply eat for for its own sake is clearly wrong. The Roman elites would indulge in food, then vomit it up to have another meal. It is easy to see that this is wrong, especially if you are undernourished.
Similarly, there are those who even today eat human flesh. This is disgusting to normal people, and condemned by all but a few.
Parents love their children, and give up their freedom to raise, protect, nourish and educate them. Husbands love their wives, wives take care of their husbands.
4 Sex outside marriage
Men and women marry and remain married until death.
5 Homosex and other unnatural practices.
Marriage is a great sacrament. A gift from God to allow men and women to share in the creation of other people. Sins like sodomy are disgusting perversions, punished physically by God in the days of Abraham. Such evils were against Australian laws until fairly recently.
6 Child marriage
God does not intend for very young girls to be married to older men. Nor for them to be forced into sexual activity.
There are those who promote the idea of sexual activity with the dead. This is an evil and repulsive practice.
God provided marriage, whose purpose includes the generation of children. Bestiality is another of those evil practices promoted by anti-Christian groups.
God expects us to be truthful, particularly to those entitled to the truth. We are not required to reveal our age or address to strangers.
Abortion is murder of a child. The Lambeth Conference of 1930 effectively did away with the sin of abortion for many Protestants. Today there is no scientific doubt that a human life begins at conception.
God provided marriage as a sacrament to give us families. To use this gift to frustrate its purpose is to denigrate this gift and turn it into something it should not be.
12 How do we know?
The natural law is written on the human heart (Rom 2:14).