What was revealed to man as the rule for obedience?

The moral law is understood as the revealed will of God, which serves as the ultimate standard for human behavior and obedience. It encompasses the principles of right and wrong that are part of God's character and order for creation. In the context of the Westminster Shorter Catechism, the moral law is particularly articulated in the Ten Commandments, which outline fundamental duties to God and to one another. This law is intended for all people, not just a specific cultural or historical group, providing a timeless guideline for ethical conduct and spiritual responsibility.

The moral law’s significance lies in its foundational role in Christian ethics, guiding believers in their relationships with God and others. While teachings of the apostles and the sacrificial system have their importance in the narrative of redemption and doctrinal teaching, they do not serve as the comprehensive rule for obedience in the same way the moral law does. Cultural norms may vary greatly and are subject to change, whereas the moral law is unchanging and rooted in divine authority. Thus, the moral law is correctly identified as the rule for obedience revealed to humanity.