Says who? Why is it not immoral to damage oneself? Why is it not playing God to determine morality in cases where one damages another?
If a man can compel the public to specific action on his part when he harms himself, the public can rightly regulate his private actions.
Only if he tries to harm himself.
God's law is negative, that is to say, that which one cannot do, with the implication at all else one can do.
God forbids many things which have nothing to do with harming others.
You damage yourself in innumerable ways every day of your life. Your body belongs to you. If it doesn't, then tell me to whom it belongs?
God's law makes no mention of damage to yourself, unless it be to your immortal soul, or your otherwise relationship with Him.
The moral guide found in His Word is what we call the Golden Rule, spoken by Jesus in both Matthew and Luke. Transgression thereof is immoral. There is no way to apply the golden rule to yourself without respect to others.
We have two kinds of laws, malum in se, that which is wrong in itself and malum prohibitum, that which is wrong only because of a law. The malum prohibitum law is enacted under the states' police power, and severe strictures, none of which strictures are followed today.
These are the "crimes" you say exist that harm no one. That they exist is no way means they are right, only that a constituency, not a majority, with money and political influence got them enacted.
The government has otherwise no constitutional pathway into the private practice of a citizen, for the state is the people thereof and the constitution created the "government".
Only if he tries to harm himself.
And the only place that is valid at all is in a socialism which is by definition Godless but for the state.
God forbids many things which have nothing to do with harming others.
Possibly. I don't know everything. Show me.