I am not a practicing Christian, but I am Christian-friendly. Christianity, and its related institutions or traditions, is basically the “operating system” by which Western Civilization runs. There are other good operating systems. iOS and Android are both pretty good. China uses Confucianism and Japan uses Buddhism. But, Christianity is the one that we use.
Since a lot of discussion these days is taking place among Christians, I think it is useful to translate some Christian concepts into forms that non-Christians can make more sense of.
An old idea in the West, which links government, science and religion, is the notion of Natural Law. I will try to summarize.
Today, we would probably say that “Natural Law” is a “Law of Nature.” For example, gravity, or thermodynamics. If you jump off a tall building, you will get hurt. If you put your hand on a hot stove, you will get burned. This is not hard to understand. But, if God Created the Universe, then certainly Natural Law is also God’s Law. It is God’s Law that, if you jump off a tall building, you will get hurt. Or, from this natural cause and effect, you can then create principles of behavior. God’s Law is: don’t jump off tall buildings, and don’t put your hand on hot stoves. Or, as we would wish God to be not quite so informal: Thou Shalt Not Jump From Tall Buildings, Nor Put Thy Hand On Hot Stoves.
This is not hard to understand in terms of the physical world. But, there is cause and effect also in human affairs. For example, people who do crystal meth usually come to harm. It is not quite as straightforward as jumping off a building, but the outcomes, at least in a statistical or actuarial sense, are almost as certain. This causes harm to themselves, and inevitably, to others around them — their family, their parents, their neighbors, their society. It is thus “immoral” — actions which cause harm to yourself and others. “Immoral” behavior is basically destructive/harmful action, and “moral” behavior is constructive/beneficial action. Lose/lose behavior is immoral. Win/lose behavior might be immoral, if the overall outcome is a net destructiveness — if the loss is more than the gain. Win/win behavior is moral.
Thus, you could say that God’s Law is: crystal meth use is destructive, and thus immoral, from which we get the principle, which could also be called God’s Law: Thou Shalt Not Do Crystal Meth. We can also get the real-world legal statute: crystal meth use/sale is a crime and comes with a criminal punishment. Some of God’s Laws are human laws — Thou Shalt Not Kill — and some do not seem to come with human sanction — Thou Shall Put No Other God Before Me.
Crystal meth use is not too hard to understand. We are generally in agreement regarding the causes and likely effects here (although people do it anyway). Premarital sex, or promiscuity, or adultery are cloudier issues. And yet here too, there are causes and effects. Some outcome pertains; and it seems like the consequences are vast, although hard to define in their totality. God’s Law is that there are effects that arise from these causes; and that these effects are generally destructive. From this we get rules of behavior: Thou Shalt Not Commit Adultery. However, to accurately analyze, understand and express these threads of cause and effect would challenge the brightest intellects of a generation. Even if they arrived at the right answer, for average and subaverage people to then make sense of it would be near impossible. Thus, people in general tend to rely upon “faith,” that God’s Law (principles based on cause and effect, with the intent of avoiding harm and producing positive outcomes) as it is expressed to them is correct, and they should follow these Laws without asking too many questions, or presuming that God’s Law is in error, and they have all the answers. Even if you look upon God’s Law as expressed in the Bible as a matter of cultural inheritance, the accumulated and refined wisdom of a hundred generations, four thousand years of human trial and error experimentation recorded in the form of anecdote rather than a message conveyed via burning bush from the Almighty, the outcome is much the same either way. If we do consider it direct communication from a higher intelligence, can we not say: good advice! There is cause and effect, from which we derive rules of behavior. Don’t jump off tall buildings, do crystal meth or commit adultery.
You can extend this even to the afterlife. It is pretty clear that God does not have a police force here on Earth, or a justice system. The punishments are in the nature of cause and effect. But, it is harder to say, for the Afterlife. You could say that the punishment for breaking God’s Law is that you won’t get into heaven. Sometimes this is seen as petty and arbitrary. For example, if God decrees that you must wear a blue hat on Wednesday, can we really imagine that we will be punished for such a thing? But what if, instead of arbitrary punishment, it is advice? Whether your version of Heaven is Christian or Hindu or Buddhist, commonly there is some kind of requirement to get there, which is basically to be “good.” Some kind of condition must be fulfilled to get off the “wheel of rebirth” or “samsara.” Only heavenly people get into heaven. In heaven, people only do things that bring good to others, not harm, and thus, the only people who are allowed in there are those who, on Earth, did things that created good, not harm. They were “moral.” God’s Law here is, again, cause and effect, but not only in our earthly world, but in the afterlife. You just aren’t going to qualify if you keep doing that stuff. Don’t say I didn’t warn you.
The New Age-y people will talk of “Service to Self” (“bad”) and “Service to Others” (“good”). On Earth, people eventually graduate to an incarnation in one of these other worlds when they polarize toward one or the other. (Reincarnation was regular doctrine of the Catholic Church until the mid-sixth century A.D.) By “polarize” I mean that: They become very good, or very bad. Then, they go to a place where everyone there is just like them. One is called “heaven” and the other, consisting of people who only cause harm to others for personal gain: “hell.” In Heaven, the pattern is cooperation for mutual benefit in an egalitarian society. In Hell, the strong enslave the weak.