Romans 2:14 : For when Gentiles that have not the law do by nature the things of the law, these, not having the law, are the law unto themselves. Macknight gives a more exact translation of Paul's language: "When therefore the Gentiles, who have not a law, do by nature the things of the law, these persons, though they have not a law, are a law to themselves." You will notice that he puts "the" before "law" only once. In that respect he exactly represents Paul. The Gentiles had no revealed law, and so they were a law un-to themselves. The Gentiles never had the law of Moses, but there are certain fundamental principles that inhere in the nature of our existence and in our relations to one another. Some things are right, and some things are wrong, within themselves. If a man never had a revelation from God, he would know that it was wrong to murder his fellow man, or to rob him of his possessions, or in any way to infringe on his rights. Cain sinned in killing his brother and felt his guilt, though we have no record that God had told him not to kill. God's moral law is the same to all nations. The moral requirements of the law of Moses are the things which the Gentiles might do by nature. The Jews did these things by revelation; the Gentiles, by nature; that is, in so far as they did them at all. But let us remember that the law under which any person lives condemns him, if he does not keep it perfectly. Paul does not say that the Gentiles lived up to their natural law any more than the Jews lived up to the revealed law. On the contrary, he was seeking to show that all were sinners and needed the gospel of Christ to save them. But they did have an idea of right and wrong.