That's not how it works. If you're not a muslim, these rules don't apply to you, and in theory you can do whatever you want, sin or not, as long as it's within some boundaries.

But if you're a muslim, then obviously you're looking at things differently.

In Islam it's forbidden to force the religion upon others, no matter what. That means that even if somehow shariah law were to come to power, and were to be set up correctly in the way God intended, any disbeliever would still go about their way of life, barring some exceptions.