Legalism is harder to avoid than you might think. Don’t assume you’re not a legalist just because you’re not trying to work your way into heaven. It’s not that simple.
As we saw last time, the Pharisees believed they could keep the Mosaic law through their own efforts. But that wasn’t the full extent of their legalism. They also took simple elements of God’s law and buried them under a mountain of fine print. John MacArthur elaborates on this in his sermon, “Jesus Is Lord of the Sabbath, Part 1”:
It was God who defined Sabbath in Genesis 2:3, He ceased completely from the work of creation. And so, Sabbath came to refer to that day when people ceased working. That’s all the Old Testament says. It simply says you’re not to work. . . .
But the hypocritical Pharisees and scribes had developed all kinds of things to make Sabbath worse than every other day because of its unbelievable restraints. . . .
You couldn’t travel more than three thousand feet. Some say you can’t go more than nineteen hundred and ninety-nine steps, if you take the two thousandth step, you’ve violated Sabbath. This would be from Friday when the sun goes down till Saturday when it goes down. . . .
No burden could be carried that weighed more than a dried fig, or half a fig carried two times. . . . If you threw an object in the air and caught it with the other hand, it was a sin. If you caught it in the same hand, it wasn’t. If a person was in one place and he reached out his arm for food and the Sabbath overtook him, he would have to drop the food and not return his arm, or he would be carrying a burden and that would be sin. A tailor couldn’t carry his needle. The scribe couldn’t carry his pen. A pupil couldn’t carry his books. . . . Wool couldn’t be dyed. Nothing could be sold. Nothing could be bought. Nothing could be washed. A letter could not be sent. . . . No fire could be lit. Cold water could be poured on warm, but warm couldn’t be poured on cold. It goes on and on.
The Pharisees’ proclivity for such absurdly detailed laws provoked a blistering rebuke from the Lord. Drawing from Isaiah 29:13, Jesus renounced their burdensome legal system: “In vain do they worship Me, teaching as doctrines the precepts of men” (Mark 7:7).
Thankfully, we don’t have to live under the oppressive minutia of pharisaical rules. Nonetheless, many Christians do live their lives in bondage to a similar strain of legalism—one where their Christian identity is largely defined by man-made rules.
That was certainly the case in my earliest experiences as a new Christian. The church I attended had roots in the holiness movement, and the pastor was certainly old school. He believed that salvation was solely by God’s grace, but maintaining that salvation was another story altogether.
My early Christian education primarily revolved around what not to do. Drinking, gambling, dancing, and close proximity to the opposite sex were all strictly taboo. Maintaining that code of conduct made me a member in good standing at my local congregation. Admittedly, I believe following those rules spared me from a lot of personal grief as a young man. But trying to live out those prohibitions was detrimental to my theology—I developed an inverted view of sanctification, believing that good works were the requirement rather than the natural fruit of spiritual regeneration.
That sort of behavioral sanctification has become synonymous with the fundamentalist movement in America. It’s unfortunate, because fundamentalism has far more noble origins. It was the bulwark against the liberal theology that invaded America a century ago after destroying the Protestant churches in Europe. John MacArthur acknowledges the heroic biblical roots of fundamentalism:
Evangelicals from both sides of the Atlantic united in writing and publishing a series of articles titled The Fundamentals. Originally published in twelve volumes, those articles laid the basis for a movement that became known as fundamentalism. With men like J. Gresham Machen, James Orr, and R. A. Torrey leading the way, fundamentalism employed sound doctrine to combat liberalism, higher criticism, evolutionary theory, and modernism.  John MacArthur, Reckless Faith (Wheaton, IL: Crossway, 1994), 93–94.
Sadly, almost immediately after its greatest triumph, the fundamentalist movement began to splinter and then morph into a completely different animal. One faction began to pursue academic credibility to an unhealthy and compromising degree. The other side overreacted by shunning serious biblical scholarship altogether and shifting their focus to matters of external behavior and appearance.
This right wing of the fundamentalist movement was relentlessly fragmented by militant separatism. Legalism led to an extreme emphasis on external issues. Petty concerns often replaced serious doctrine as the matter for discussion and debate. This branch of the movement quickly reached the point where some of its adherents spent more time arguing about men’s hair length and women’s clothing than they spent defending the real fundamentals of the faith.  Reckless Faith, 95–96.
Fundamentalists are now widely derided as legalists by most Christians, and as party poopers by an unbelieving world. And that’s a tragic outcome for a movement that I still hold strong affections for, with founders whom I count among my spiritual forefathers.
Nonetheless, the trajectory of fundamentalism furnishes us with a powerful lesson on the dangers of creeping legalism. Spiritual identity must not be bound up in external behavior or appearance. Yet that’s what we see every time we drive through an Amish community. It’s what we hear every time a Seventh Day Adventist admonishes us about Sunday worship. And it’s what we display every time we start legitimizing our Christianity on the basis of the things we do or don’t do.
Does this mean we shouldn’t concern ourselves with external righteousness? In the words of the apostle Paul: “May it never be! How shall we who died to sin still live in it” (Romans 6:2). Our growth in righteousness matters to God. But as I stated earlier, our sanctification is the result of true conversion, not the guarantee. That’s not to say that righteousness occurs passively, but rather when you “work out your salvation” (Philippians 2:12) you are only able to do that because God “is at work in you, both to will and to work for His good pleasure” (Philippians 2:13). It says “His good pleasure” and not “our self-restraint”—if our good works only come through gritted teeth, they may well point to a heart that is not yet regenerated by the Holy Spirit.
Ezekiel beautifully points to the external righteousness that manifests in the lives of those who are internally transformed by the Holy Spirit: “I will put My Spirit within you and cause you to walk in My statutes, and you will be careful to observe My ordinances” (Ezekiel 36:27). We should give glory to God for even the good things we do. As John MacArthur argues, justification isn’t where God’s work ends, but rather where it begins:
Those who argue against lordship salvation often base their theology on the faulty assumption that the work of God in salvation stops with justification. The rest, many believe, is purely the believer’s own effort. Sanctification, obedience, surrender, and all aspects of discipleship are left up to believers to do or not do as they choose. Thus while touting salvation by grace apart from works, they have actually established a system that is almost wholly dependent on human works for any measure of practical righteousness.
Thankfully, the gospel according to Jesus does not abandon believers to their own energies. The glorious justification our Lord spoke of is only the beginning of the abundant life He promised (cf. John 10:10). “He who believes in Me, as the Scripture said, ‘From his innermost being shall flow rivers of living water’” (John 7:38). The salvation He promised brings not only justification, but also sanctification, union with Him, the indwelling Holy Spirit, and an eternity of blessing.  John MacArthur, The Gospel According to Jesus, 3rd ed. (Grand Rapids, MI: Zondervan, 2008), 200.
God is the author of our salvation and the power source for a transformed life. True liberty from the shackles of legalism awaits those of us who find our Christian identity and value, not in what we do or don’t do, but in Whom we belong to. In other words, our position in Christ is a far more trustworthy gauge of our spiritual status than our behavior.