This post is in response to a question, although it is not a direct answer to that question, the question is what got my mind working on this answer.

Here's the question: Is it, a violation of separation of church - state to invoke biblical morals or biblical definitions of marriage or sin into law?

I often hear people say you cannot legislate morality. In fact, I believe all legislation is legislating morality. Let’s chose 3 random laws and see that they all convey some moral imperative.

Speed Limit – this law implies that as a society we value the worth of human life. Therefore there are restrictions on how you can drive so as not to endanger yourself and others with what is undoubtedly an extremely dangerous piece of machinery.
Voting age – this law implies that we as a society value the democratic process deeply. And we desire to have well-informed voters making decisions for our country. It is safe to assume that school-aged children are not well informed and would not make good voters.
Pay Taxes – this law makes it clear that we believe that many things must be done for the good of our entire society. The only way to pay for these things is for everyone to chip in. People won’t contribute without being forced so we make it a law.

Here are 3 laws seemingly unrelated to morality that have a moral principle attached to them. That human life is important, that freedom [therefore democracy] is important, and sacrifice for the common good is important.

If all legislation is tied to morality, then we have a duty to legislate morality.

If we believe it is morally wrong to do activity X, then we are wrong not to make activity X illegal. So let’s pick an obvious example; murder. Everyone I have ever known believes that murder is morally wrong. This is a non-gray area, and consequently, murder is illegal. Here’s another example; lying. Most people believe that lying is wrong under most circumstances. Consequently, we have laws against lying in important circumstances, such as, for example, in a court of law.

But what about areas where there is genuine debate in our society about what is moral and not? Then it seems that there must be some compelling reason to change the laws as they are currently established. For those people who, for example, believe that it is morally allowable to smoke marijuana, they would need to show some reason why the state would be better off by allowing it and changing a long-standing law. That is almost always a hard way to go.

Here is the final thought for this post - SOMEBODY'S morality is going to be reflected in every law.

(I have divided this post in two parts because it was entirely too long. Please come back tomorrow and read about who decides morality.)