Law

You say that Sarah thinks that laws are created only by societies. As a secular humanist, her views of law are rightly this. Secular humanists believe in what is known as "positive law" in which man, or society, devises his own rules. For a secular humanist, law and rules bring order to their lives, yet they are subject to change. Positive law rotates on the fact that only humans know what is best for their society, so they clearly reject the idea of divine law, or the idea that God governs His people and has put into place a set of rules that we, as His people, must follow.

In answer to your question, governments are not the ultimate authority for creating laws. As Christians we believe in divine law, or natural law, which holds to the idea that God, our supreme creator, not only created the Heavens and the Earth, but law as well, and put the idea of law to use through the creation of absolute laws, or rules that we must follow. God laid out his plan for creation, and put rules into place from the very beginning. Adam and Eve, after breaking God's only rule, were banished from the garden because they went against God's set rules. We of course see this idea of rule breaking and punishment still alive today. After the Garden of Eden, God laid out a list of rules in the Ten Commandments that he gave to Moses to safeguard and teach to the people. It is easy to think of God as a strict parent that keeps us all on a tight leash, but in reality the laws that God makes mirror His nature. We can therefore be more like God if we choose to follow the rules that He has set out for us, and it is this that He wants us to do.
While it may seem that governments make the rules in our country, it is ultimately to God that we should be answering to. God of course wants us to respect the leaders that he has put into place to help govern us, but whenever something in the law contradicts God's word we should be prepared to go against the government to follow our Creator and ultimate law giver. God is the ultimate authority for the creation of laws as he created even the idea of law itself, and although government may try to persuade us differently, is it God to whom we answer in the end!