William MacDonald emphasizes that keeping God's commandments is not synonymous with legalism, which is the misguided attempt to earn God's favor through lawkeeping. He clarifies that while Christians are free from the law, they are not lawless; they are called to live in accordance with Christ's desires. MacDonald points out that the New Testament contains many commandments that serve as instructions for righteousness rather than penalties. He warns against the misuse of the term 'legalism' to dismiss godly behavior and encourages believers to adhere closely to Scripture for their moral guidance.

“If ye love me, keep my commandments.” (John 14:15) Commandments? In the New Testament? Whenever people hear the word commandments, they immediately think legalism. But the two words are not synonymous. No one spoke more of commandments than the Lord Jesus, yet no one was less legalistic than He. What is legalism? Though the word itself is not found in the New Testament, it describes man’s ceaseless effort to earn or deserve God’s favor. Basically it signifies the attempt to gain justification or sanctification by lawkeeping. That is its real meaning. But today the word is used in a wider sense to describe what are thought of as rigid, moralistic rules. Any attempt to classify certain practices as taboo is “legalistic.” In fact, the word “legalism” is now used as a handy club to beat back almost any restraints on Christian behavior or any negatives. How, then, should a Christian think in order to avoid the danger associated with “legalism”? First of all, it is true that a Christian is free from the law, but it is important to add quickly that he is not lawless. He is enlawed to Christ. He shouldn’t do as he pleases but as Christ pleases. Secondly, it must be remembered that the New Testament is filled with commandments, including a fair number of negatives. The difference is that these commandments are not given as law, with penalty attached. They are given as instructions in righteousness for the people of God. Next, things may be lawful for a Christian but they may not be profitable. They may be lawful but they may also be enslaving (1 Cor. 6:12 NASB). It is possible that a believer may have liberty to do something and yet he might stumble someone else in doing it. In that case he shouldn’t do it. Just because someone dubs a prohibition as “legalistic” doesn’t mean it is bad. People also use the word “puritanical” to denounce certain codes of conduct, but the behavior of the Puritans was more Christ-honoring than that of many who criticize them. Very often when Christians castigate accepted patterns of godly behavior as “legalism,” it may be a sign that they themselves are becoming more permissive and are drifting from their moral moorings. They naively imagine that by throwing mud at so-called legalists or Puritans, they themselves will look better. Our safety lies in staying as close to the teachings of Scripture as possible, not in trying to see how close we can get to the edge of the precipice.