Controversial Questions

Once we agree that God gets to determine ethics, that doesn't mean we're all going to be in hunky dory agreement with each other on how to make the right application. Paul warns about getting too tied up in quarrelsome matters relating to the law. Surely the Pharisees were good at it. Yet, we do not ignore the law. We still wish to love God and keep His commandments. So, how does this work when it comes to the matters of law over which sincere Christians disagree? How does one determine the difference between the principle and the application? The certain and the uncertain? The camels and the gnats?