The answer to this question will depend on your background and on your intended use of commentaries. As you consider the commentaries you may choose, pay attention to these factors.
Know What Type of Commentary You Are Looking at
As a general rule, one could view commentaries as a genre on a spectrum from “devotional” to “technical.” The more “devotional,” the more application in the commentary and the less it may explain the text. The more “technical” works may eschew personal application of the text in favor of intense examinations of word endings in the original language and other minute details (sometimes these make it hard to see the forest for the trees). Somewhere in the middle, we might find “expository” commentaries which try to strike a balance between explaining the text and giving some application (sometimes “expository commentaries” are edited manuscripts of sermons from that book of the Bible).
Generally speaking, works that focus more on the technical or expository approach may provide more help on the front end (understanding the text), while expository and devotional commentaries major more on the application (which you may be working on more toward the end of your sermon or lesson preparation, since it should be based on your understanding of the text).
Know What Commentaries Others Recommend
Ask a trusted pastor, or consult a list. Whole books have been written for the purpose of cataloging commentaries. I recommend Master’s Seminary professor James Rosscup’s Commentaries for Biblical Expositors (for more recent works, and careful to tell you their theological perspective) and Charles Spurgeon’s Commenting and Commentaries (a dated but delightful book to peruse for his comments about the commentaries; some of the works mentioned are still available while some are rare).
Know the Perspective and Quality of the Commentary You Are Looking at
Commentary authors are on a spectrum of their own. The range includes those who love the Bible but misunderstand and misapply it frequently, to those who are serious students who give helpful explanations, to unbelievers who may have helpful insights into the technical or background parts of the text, to unbelievers who seek to deconstruct the text.
Knowing the perspective and quality of a commentary can help you discern whether it would be a good use of your time and money, and, if so, can help you know how to approach it. I do not generally recommend the use of commentaries of a theologically liberal or unbelieving persuasion (except for research to know what others believe/how they have explained a text incorrectly). This, however, does not mean that conservatives are always right and liberals are always wrong; sometimes a liberal commentator may explain the text more accurately than a conservative who has misread it. Better yet, it’s great to find someone who believes the Bible AND has a clear understanding of the passage at hand, to avoid influence from false teachers (but sometimes you do need to know what false teachers are teaching so you can avoid it).
While we should be Bereans regardless of the author (Acts 17:11 – the Bereans were called noble for doublechecking the apostle Paul!), knowing that you may be using a work written by someone with doubts about the text of the Bible should especially lead you to “chew carefully” as you ingest the book. You can spit out the bones and chew the meat in some circumstances, but it helps to know there are bones before you dig in! (If not, hopefully you are discerning enough to know when you have found one. Ouch – my tooth!)
Researching and knowing the reputation of the publisher can be helpful in this regard, but it is not a foolproof way of knowing the theological perspective. Once-stalwart publishers have taken to publishing a wider ranger of perspectives than they once did, to such a degree that you cannot implicitly trust many historically conservative publishers to publish only conservative commentaries. (Some still exist that have not bowed the knee to Baal.)
Even beyond the liberal/conservative distinction, one may want to know if a commentary is dispensational or covenantal (prophetic books), authored by Presbyterian or Baptist, cessationist or continuist (book of Acts), etc. One should also research enough to know whether the author had sufficient background and skill to write a work on a Bible book. Some commentaries may be composed of rants or assertions of the author’s viewpoint without clear reasoning to support his or her viewpoint.
One more distinction you may notice when looking at commentaries: men are not the only authors. There are commentators such as Nancy Guthrie (whose work has been recommended by Bible-believing pastors). There is a spectrum of conservative to liberal with women authors just as there is with men.
Cost and Availability of Commentary
Suppose you have found a great commentary… only to find it it’s $59.95 and you’re only preaching one sermon from that book. Or you have found the perfect one… and it’s out of stock online and the bookstore can’t get it in before your deadline. It doesn’t make sense pay to an exorbitant cost (unless it is the best deal going for that book or it is rare, and you will use the book again in the future, and you can afford it, etc.) and sometimes you really cannot find the one you’re looking for.
In our next installment, we’ll talk about WHERE to find commentaries (and you may end up finding that elusive volume!), but until then, my best advice is to find 1-2 good, solid, commentaries on your book written by conservative Bible scholars. You only have so much time, and most of it needs to be with the text of the Bible, so limit yourself to a couple of commentaries if you can. Research some recommendations, and make sure you can afford, find, and are comfortable (or challenged within reason, not by something too high over your head) with your choices. Then borrow first if you can, and buy (if you need/want to).
Next: Tips for Finding Commentaries (access to the specific ones you are seeking)