Man also, as a creation of Jehovah, is subject to Jehovah’s physical laws, and since he is a moral, rational creature, capable of reasoning and of spirituality, he is equally subject to God’s moral laws. (Ro 12:1; 1Co 2:14-16)

Likewise, the moral laws of God are irrevocable and cannot be circumvented or violated with impunity. They are as sure of enforcement as are His natural laws, though the punishment may not be as immediately enforced. “God is not one to be mocked. For whatever a man is sowing, this he will also reap.”​—Ga 6:7; 1Ti 5:24.

Before Jehovah gave his law to Israel, how could humans determine God’s will for them?

Whereas from Adam’s rebellion to the Flood badness increased among the majority of his descendants, some faithful men “kept walking with the true God.” (Ge 5:22-24; 6:9; Heb 11:4-7) The only specific commands recorded as given to such men by God are the instructions to Noah in connection with the ark. These Noah obeyed implicitly. (Ge 6:13-22) Nevertheless, there were principles and precedents to guide faithful humans in their “walking with the true God.”

They knew of God’s bounteous generosity in providing for man in Eden; they saw the evidence of divine unselfishness and loving interest. They knew that the principle of headship was in effect from the start, God’s headship over man and the man’s headship over woman. They knew of God’s assignment of work to man as well as His concern for proper care of the things given to man for his use and enjoyment. They knew that sexual unions were to be between man and woman and that those so uniting were to do so within a marital relationship, that they would ‘leave father and mother’ to form a lasting union instead of a temporary one (as in fornication). From God’s command regarding the use of the trees of the garden of Eden and the tree of the knowledge of good and bad in particular, they could appreciate the principle of ownership rights and due respect for such. They were aware of the bad results coming from the first lie. They knew of God’s approval of Abel’s course of worship, God’s disapproval of Cain’s envy and hatred of his brother, and God’s punishment of Cain’s murder of Abel.​—Ge 1:26–4:16.

Thus, even without further specific statements, decrees, or statutes from God, they could draw on these principles and precedents to guide them in different, but related, situations that might develop. Centuries later, Jesus and his apostles viewed pre-Flood matters in this way. (Mt 19:3-9; Joh 8:43-47; 1Ti 2:11-14; 1Jo 3:11, 12) Law means a rule of action. By God’s words and acts they had the means for knowing something of his way, his standards, and this should be the rule of action, or law, for them to follow. By doing so, they could ‘keep on walking with the true God.’ Those failing to do so were sinning, ‘missing the mark,’ even though there was no law code to condemn them.

Following the Flood, God stated to Noah the law, binding on all mankind, that allowed the eating of flesh but prohibited eating of blood, and He stated the principle of capital punishment for murder. (Ge 9:1-6) In the early post-Flood period, men such as Abraham, Isaac, Jacob, and Joseph showed genuine concern for God’s way, his rule of action. (Ge 18:17-19; 39:7-9; Ex 3:6) Though God gave certain specific commands to faithful men (Ge 26:5), such as the law of circumcision, there is no record of his giving them a detailed law code to observe. (Compare De 5:1-3.) Nonetheless, they had not only the principles and precepts of the pre-Flood period to guide them but also additional principles and precepts to be drawn from his expressions and dealings with mankind in the post-Flood period.

Thus, although God had not given a detailed law code, as he later did with the Israelites, men were not without some means for determining right and wrong conduct. Idolatry, for example, had not yet been specifically condemned by a stated law. Nonetheless, as the apostle Paul shows, such practice was inexcusable inasmuch as God’s “invisible qualities are clearly seen from the world’s creation onward, because they are perceived by the things made, even his eternal power and Godship.” The venerating and rendering of “sacred service to the creation rather than the One who created” was against all reason. Those following such an empty-headed course would thereafter deviate into other unrighteous practices, such as homosexuality, changing “the natural use of themselves into one contrary to nature.” Again, even though no specific law had been given, such practice was obviously contrary to the way of God the Creator, as the very structure of the male and female manifested. Man, having been originally made in God’s image, had intelligence sufficient to see these things. Hence, he was responsible before God if he went contrary to God’s way; he was sinning, ‘missing the mark,’ even without a specifically stated law to charge him with guilt.​—Ro 1:18-27; compare Ro 5:13.