There is indeed such a system. It is simply not humanly possible to achieve.
You stated that A) Because something was wrong B) it should be banned. Adultery is wrong. It is bad for society. It should therefore be banned. Also lying. Also pornography, and homosexuality, and (heck, so long as we are imposing our moral vision on people Because We Can), cheering for the Patriots and Auto Salesmen who do their own television commercials, along with any form of speech that advocates for allowing those things.
Since the only perfect justice (and, as you have pointed out, JUSTICE MUST BE ENFORCED OR IT DOES NOT EXIST, meaning that, if it not enforced always and perfectly, it does not exist) available is God's Justice, then we must impose completely the moral rulings of the Christian faith (being, I have decided, the correct one) on EVERYONE.
Or else, after all, we won't be "Just". And making sure that everything is Just is, of course, the reason we have Government.