What does natural law teach?

from the old testament

• Natural law is implied by the moral content of the Ten Commandments (Exodus 20:3-17). The Bible often highlights the benefits of choosing good and avoiding evil, which is the basic teaching of natural law.
• The Bible presumes the existence of natural law and appeals to it on multiple occasions (Exodus 20; Psalm 34:14; Psalm 37:27).

from the new testament

• The New Testament also shows the presumption of natural law (Romans 1).
• Matthew 22:37-40, summarizing the Ten Commandments, teaches our duty toward God, “Love the Lord your God,” and our duty toward our fellow man, “Love your neighbor as yourself.” This means that “the good” that we are seeking is the love of God and then, following that, the love of man, and “the evil” that we are avoiding is the opposite.
• Romans 1 is the most common source for natural law in the Scriptures. According to Romans 1:19-20, nature teaches that God exists. Paul goes on to say that people knew this fact but refused to worship God or give him thanks (Romans 1:21), and so we can also say that the natural law teaches that the worship of God is a moral imperative.
• The concept of obedience to authority and peaceable order within human society is a consequence of natural law. Rebellion is contrary to the natural law, as is disrespect for authority and disregard for propriety. This is because our God is a God of order (1 Corinthians 14:33), and so his creation reflects that same reality.

implications for today

St. Thomas Aquinas linked natural law to divine law, asserting that natural law is a participation in the eternal law, which is the rational plan by which all creation is ordered. Aquinas believed that the fundamental principle of natural law is that humans should do good and avoid evil

When Thomas Jefferson wrote, "We hold these truths to be self-evident…" he was referring to natural law. Jefferson considered the equality of man, and life, liberty, and the pursuit of happiness (purpose and livelihood) to be born directly from the nature of humanity. Civil laws are derived from natural law. Natural laws are somewhat vague (citizens should be safe), so governments develop more specific civil laws (violent criminals will be prosecuted).

Natural law and conscience are closely related because both deal with our inherent sense of right and wrong. Natural law provides universal moral standards, while conscience is the internal awareness that guides individuals to recognize and respond to these moral truths. In essence, conscience acts as a personal, inner compass, shaped by the principles of natural law, but can be influenced by personal experiences, culture, and choices. Natural law reveals the right way to live, and as such, it also reveals that men are not living that way. It shows that something is broken, that there is a problem.

But natural law cannot explain why the order is broken. It cannot tell us what the problem is (sin) or how it came to be. For that, we need God’s special revelation, His Word. The Bible teaches the absolute necessity of God's grace and His plan of salvation. The only name by which men may be saved is the name of Jesus Christ (Acts 4:12).