Sam Storms, Tough Topics: Biblical Answers to 25 Challenging Questions 
(Wheaton: Crossway, 2013), 311–12, 314–15 [32-page sample PDF]:
Legalism has been defined in a number of ways, but here is my attempt: Legalism is the tendency to regard as divine law things that God has neither required nor forbidden in Scripture, and the corresponding inclination to look with suspicion on others for their failure or refusal to conform. . . .
2. Do you elevate to the status of moral law something the Bible does not require? . . .
Hold your conviction with passion and zeal, but do not seek to enslave the consciences of others who may disagree with you. . . .
One unmistakable sign of a legalistic spirit is the tendency always to be looking for what’s wrong in other people’s lives in order to judge them, instead of looking for what’s right in order to encourage them. . . .
Legalists feel good when they can identify another person’s errors. It reinforces their feelings of superiority. They actually think themselves more spiritual, more godly, and more favored and loved by God.
Here’s an antidote.
Legalism often is a failure to understand the gospel’s implications for sanctification. Perhaps more often it is a failure to understand the implications of the sufficiency of Scripture! Grudem puts it this way: “With regard to the Christian life, the sufficiency of Scripture reminds us that nothing is sin that is not forbidden by Scripture either explicitly or by implication.” (Bible Doctrine, 61) Thank you for another great quote…
That’s right on the money and pretty much sums up my heart and thoughts during the years that Jesus and the gospel were marginalized. The problem is that it’s not always clear when you’re in the midst of it. Add to that liberal legalists (yes, there is such a thing). Hence, I wrote: Gospel Amnesia
If I take his definition (which I do not sure holds throughout the NT), how do I distinguish Romans 14:1-5 from his view of legalism? There was condemnation occurring by the weaker brother? Was the weaker legalistic? Or does Paul even go there? The answer is, that Paul does not even go toward legalism. Judging, condemning, and legalism are used in differing nuances in the NT.
Thanks for raising this question, Frank. So many disagreements dissipate when we carefully define terms.
There are at least two senses of legalism:
1. I grant your point that technically legalism is attempting to obtain salvation by works.
2. But usage determines meaning, so I don’t think we can limit the definition to that one sense since today many people use the word legalism to denote something different than that. Sam Storms fits here; and he’s also careful to say that we can be “legalistic” (as opposed to being “legalists” in the first sense of the term).
Related:
1. John MacArthur on how to serve Christians who are needlessly restrictive
2. C. J. Mahaney and Doug Moo on legalism
3. Bob Gonzales, “Confessions of a Recovering Legalist”
4. Dave Swavely on judgmental statements
5. Graeme Goldsworthy on “Legalism: Evangelical Judaism”
6. How to Disagree with Other Christians about Disputable Matters
Thanks Andy. Appreciate the comments. I am commenting on your quotations as I have not read his book.
As a believer seeking His understanding, I want to define my terms from the NT. I want to know what the NT is saying and its own definitions. I, then, pursue change to my erroneous thought patterns in order to conform to the Lord’s definition.
I certainly concede that language may change according to its usage. I also concede that one might have to footnote current usage in debate. From a NT perspective though, I don’t think the debate (or, attack) is advanced to any form of edification when we adopt relativistic definitions. Usage defines meaning but when we pour a meaning back into the NT which is not there, we are in danger of misdefining and misapplying the passages involved. I know you know this, but Sam Storm needs to fence in his definition from the NT, not from his experiences. Sam gives the impression of sound exegesis which makes his statements potentially damaging and not helpful to the body of Christ.
Does the word “legalism” or “legalist” ever appear in the Bible? It doesn’t in the NIV or the ESV (I didn’t check others). So part of the debate is about how to define an extrabiblical term.
Agreed. I have not checked if it has a usage from a historical theology perspective.
“Legalists feel good when they can identify another person’s errors. It reinforces their feelings of superiority. They actually think themselves more spiritual, more godly, and more favored and loved by God.” Yes, and it works both ways–if I take a more “conservative” stance than my brother does or if I take a more “liberal” stance than my brother does and look down on him as a result.
Legalism is often portrayed as the sole purview of those who take a more conservative stance, the assumption being as long as you’re not a Fundamentalist, for example, you can’t be a legalist. Not the case. It’s a temptation we can all fall prey to. When we think, “I thank God I am not as other men,” we are already there.
Totally agree, Steve. Jerry Bridges calls that “judgmentalism in reverse.”