One potential reason that is often given in such cases is morality, often based on the Bible. The idea here is that wrong things should be illegal. However, this explanation is insufficient. There are many things that are wrong that should not be illegal. Some wrong things can’t be legislated because we humans cannot detect when they are occurring. Lust and coveting, for example, are wrong, but how could you tell if someone is doing those things?
But even beyond that, some wrong things are none of government's business. Government has authority over some areas of life, but not all areas. So some things, which might be wrong, simply do not fall under government’s jurisdiction, and thus, government has no authority to punish those who do them. For example, if a child disobeys his parents – perhaps he ate candy he was told not to eat – that is wrong. But the government has no jurisdiction to punish the child for the wrong he did. The punishment should be decided and administered by the child’s parents. Government simply has no authority to step in and haul the child off to juvenile hall for eating the forbidden candy. Similarly, if two adults engage in premarital sex, it is wrong. But it is not government’s responsibility to punish them for what they do in the privacy of their homes. A third example would be someone who swears. It might be wrong, but saying an expletive ought not to send you to jail or even cause you to pay a fine.
Because government has limited authority, there must be principles that explain the limits of that authority and explain what falls under government’s jurisdiction and what does not. It is very important to know WHEN it is government's business to get involved and WHY government should be involved in those cases if we are to make law properly.
The principles that show us when government should be involved in regulating or punishing behaviors are known as inalienable rights. Government's primary purpose is to protect inalienable rights and, thus, things that violate inalienable rights should be illegal.
If you don’t know what inalienable rights are, check out my 5-part series:
The Inalienable Rights Series
Part 1: What are Inalienable Rights?
Part 2: The Source of Inalienable Rights
Part 3: Liberty in Society and Government
Part 4: Government by Consent of the Governed
Part 5: Some Common Misconceptions
It should be noted here that no one can create inalienable rights just by dreaming them up. Like the principles of mathematics, they are discovered, not invented. They all logically follow from basic principles and apply to everyone. Thus, they form a solid basis for differentiating the things that fall under government’s jurisdiction from those that do not. In short, any behavior that violates the inalienable rights of anyone should be illegal. Government has a duty to make such behaviors illegal and to provide punishment for the violation of rights in order to protect those rights.
So, with that in mind, murder, which is a violation of the right to live, should be illegal. Rape and slavery, which are violations of the right to liberty, should be illegal. Theft, which is a violation of the right to own property, should be illegal.
On the other hand, premarital sex, though wrong, is not a violation of anyone's rights as long as it is consensual. Thus, it is none of government's business. The same goes for homosexual acts. They may be wrong, but punishing them does not fall under government's jurisdiction. Disobedient children, assuming they have not violated the inalienable rights of anyone, should not be punished by government. Taking God’s name in vain, though serious enough to be forbidden in the Ten Commandments, does not fall under government’s jurisdiction because it violates no one’s rights.
At this point, many conservative Christians tend to object. They don’t like idea that not all wrong things should be illegal. They point out that God’s laws are the ultimate foundation for all morality and truth. They question the principles of inalienable rights. They point out that inalienable rights can only exist if there is a God. I’m not unaware of these arguments. However, those who claim that laws should be based simply on morality or the Bible are making some very serious mistakes.
For one, when you conflate “wrong” with “illegal,” you are allowing government to become the arbiter of truth rather than leaving that role to God. God decides what is right or wrong and it is God’s job to punish wrongdoing. In some cases, God delegates the authority to punish evil to government. But in other cases, He doesn't. If it was true that everything that is wrong should be illegal, that means government is doing God’s job. If you think government is the punisher of all evil, then you are displacing God and elevating government to an improper role.
Not only that, but when you conflate “wrong” and “illegal,” people tend to think that if something is legal, it must be okay. Thus, there are lots of people, for example, who think abortion is okay because it's legal. They are looking to government as the arbiter of right and wrong because they think “wrong” and “illegal” are the same thing. People also get the opposite idea too. If something is illegal (like sharing your faith in some countries), people think it's wrong. Again, the problem is a lack of understanding of the proper role of government and its limitations.
Another problem that occurs when people don't understand the proper role of government is government overreach. If you think all wrong things should be illegal, you tend to advocate for government to step in whenever there is something you don't think is right. This grows government to a huge size and gives it far too much power.
It has been said that a government that is big enough to give you everything you want is a government big enough to take everything away from you. It is similarly true that a government big enough to disallow every wrong thing is big enough to disallow (or allow) whatever it wants and to try to elevate itself to the place of God in the lives of the people.
So, I’ve explained why it is important to understand which things actually do fall under government's jurisdiction and which do not. It is so important to make the right argument about how we should make law. You can't say, or even imply, that being wrong is the sole reason a behavior should be illegal without assigning government the wrong role and usurping God's place as arbiter of right and wrong. Instead of simply saying that something is wrong, we need a rationale for why a particular sin falls under government's jurisdiction, not just God's. In other words, we need to show how a behavior violates inalienable rights in order to justify making it illegal.