Review - Conscience: What It Is, How to Train It, and Loving Those Who Differ (Part 1)

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The goal of this book is “to put conscience back on your daily radar, to show from Scripture what God intended and did not intend [the] conscience to do, and to explain how your conscience works, how to care for it, and how not to damage it.”1

Definition & Understanding

As their titles suggest, the first two chapters deal with defining the conscience. Chapter 1 defines the conscience as “your consciousness of what you believe is right and wrong.” Chapter 2 examines how the New Testament writers taught about conscience and develops a biblical understanding of the conscience from these data. Included in this is a definition of the “weak conscience”: an “uninformed moral consciousness.”2 As we’ll see later, this is the first of two definitions given in this book, and this presents a dilemma.

Chapter 3 answers, “What Should You Do When Your Conscience Condemns You?” The answer is the gospel, for nothing but the grace of God in the atoning work of Jesus can free us from guilt. This applies to the lost man approaching the cross with his guilt and the long-time believer who must again and again return to God in confession and seek forgiveness. We must never allow our guilt to become a tool for the accuser to bring us to despair.

In chapter 4, the authors admonish us not to go against our consciences. But they caution that the conscience is not perfectly reliable. Building on the definition of “weak conscience” from chapter 2, they explain that the conscience might not be theologically correct. They add to the definition of “conscience” (“your conscientiousness of what you believe is right and wrong at any given point in time”), and they explore the ways the conscience can change over time. These include, “hardening,” “influence of other people,” and “conforming to the truth.”

Sinning Against vs. Calibrating

One of the great pearls of this book is the discussion of the difference between sinning against your conscience and calibrating your conscience. “You are sinning against your conscience when you believe your conscience is speaking correctly and yet you refuse to listen to it.” But,

You are calibrating your conscience when Christ … teaches you through his Scripture that your conscience has been incorrectly warning you about a particular matter, so you decide no longer to listen to your conscience on that one matter … In the early stages of calibration, deciding not to listen to your conscience may feel like you’re sinning against it.3

This was an insight to me and is grounded in Peter’s vision in Acts 10.

This calibration, the authors advise, must come by educating it with truth (which must include both biblical truth and extra-biblical truth) and with due process (it can be a long process). They use examples to explain how the calibration process will include both adding to the conscience and subtracting from the conscience. The authors offer many examples of issues on which Christians disagree.

How Believers Treat One Another

Having considered the individual conscience, Naselli and Crowley turn in chapter 5 to how Christians with differing consciences ought to treat one another. They stand on Al Mohler’s shoulders and utilize his system of triage,4 which recognizes three levels of issues.

  • First-level issues are essential Christian teachings. With those who differ on these, we cannot have “Christian” fellowship, for one can’t deny them and “still be a Christian in any meaningful sense.”
  • Second-level issues are reasonable denomination and local church boundaries. How and who should we baptize? How should the church be governed?
  • “Third-level issues are disputable matters (also called matters of indifference or matters of conscience)… how should Christians view the ‘Sabbath’?… Disagreement on third-level issues shouldn’t cause disunity in the church family.”5

One small problem with Mohler’s triage system is that the line between second-level and third-level issues is defined in a circular way. We have a duty to fellowship when we have third-level differences. A duty is something we must do regardless of whether we want to do it. However, if we find it reasonable to not fellowship over the difference, then we simply assign it to the second-level. Then our duty to fellowship goes away. It does not make sense for the test of whether the duty to fellowship exists to consist of whether or not I think this is a good time to fellowship.

Nevertheless, Mohler’s system is valuable at least as a descriptive tool. Naselli and Crowley imply that by “matters of conscience” they mainly refer to third-level issues. Throughout the book, they limit the principles to “matters where good Christians disagree.” In doing so, they run the risk of maintaining the circular problem. If I don’t want to apply the non-judgment principle, for instance, I can always say, “Well, that’s not an issue on which good Christians disagree. It’s a second-level issue, so I should judge, rebuke, and separate.”

The authors then provide an easily understood exposition of Romans 14 and 1 Corinthians 8-10. This discussion leads to the highly useful Table 9: Paul’s Solution of Love.6 Although I have a few issues with it, the book’s treatment of these passages is concise and masterful.

Some Helpful Insights

Some significant and helpful insights are made by the authors. For instance, on Table 9 there is exact correspondence between “Eating” and “Strong Conscience” (and between “Doesn’t Eat Meat” and “Weak Conscience”). At the same time, there is a lack of correspondence between “Weak Conscience” and the state of being theologically misinformed about the general uncleanness of the meat. Note especially that the fifth column describes “Weak” believers who welcome without judging, unlike their counterparts in column 6 who deny the faithfulness of their meat-eating brother. They can do this only if they recognize that their brother who eats meat is not sinning. Therefore, one can be “weak” and theologically informed about the general cleanness of meat. The authors clarify,

What was Paul’s message to the weak of conscience? “If your strictness in these matters is causing you to judge others and bring division to the church, you are sinning … stop trying to force others to obey the rules of your conscience. Your conscience is for you, not them. Welcome them … Appreciate their robust conscience.”7

Yet, this man still must obey Luke 17:3, “If your brother sins, rebuke him.” Therefore, in order to not judge his brother, he must clearly understand the new teaching about meat. This is a great insight because it allows for an obedient, theologically informed weak Christian. This suggests a departure from the previous definition given for “weak conscience.”


1 Naselli, Andrew David and Crowley, J. D., Conscience: What It Is, How to Train It, and Loving Those Who Differ, Crossway, Wheaton, Illinois, 2016, Kindle location 192, P. 17.

2 Discussing 1 Cor 8:10, “Here’s the idea: If anyone sees you, who have an informed moral consciousness on this issue (i.e., you know that there are no real gods but one), eating in an idol’s temple, won’t that person’s misinformed moral consciousness be emboldened…” (Kindle Locations 426-428, P.35).

3 Conscience, Kindle 866, P. 61.

5 Conscience, Kindle 1222, P. 86.

6 Conscience, Kindle 1317, P. 94. This reviewer takes issue with the note under the center column of Table 9, “The goal of every mature believer.” Paul, in Romans 14:5-9, asks each (strong and weak) to be fully convinced in his own mind, so that he can live out his own conviction for God’s glory. This is contrary to the idea that Paul had a goal of “strong” over above “weak” (as long as they don’t despise and judge).

7 Conscience, Kindle 1324, P. 95

Dan Miller Bio

Dan Miller is an ophthalmologist in Cedar Falls, Iowa. He is a husband, father, and part-time student.

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There are 5 Comments

Bert Perry's picture

....the part about "training" one's conscience.  I see a lot--in myself and others alike--how very often, we are tempted to treat our own experience as normative for the Christian life, whether or not we derive that conscience from Scripture.  Retraining it can take a while!

Aspiring to be a stick in the mud.

Aaron Blumer's picture


Thanks for the thorough walkthru, Dan. Clearly an important contribution to the topic.
... Part 2 posts tomorrow.

Views expressed are always my own and not my employer's, my church's, my family's, my neighbors', or my pets'. The house plants have authorized me to speak for them, however, and they always agree with me.

JD Crowley's picture

I especially appreciate a review by someone who's put so much thought into the subject of conscience. Few have. Thanks, Dan.

Susan R's picture


I really enjoyed this review, and looking forward to Part 2.

I stumbled onto the idea of training my conscience around the time my brother challenged me to read the Bible cover to cover once a month. I did so for a few years, and then reduced it to 6 times a year. But boy-howdy, talk about washing of water by the Word. And I'm not talking about in depth study - just reading and reading and reading definitely re-calibrated my conscience. 

The three level triage formula is about as good as any formula one can come up with, and therefore is severely limited because of the complexity of human interaction and experience. I find that a dependence on formulas often results in a certain amount of intolerance and impatience. "Oh, you differ on this issue? Good-bye!" Out the window goes the opportunity for communication, understanding, possible discipleship... 

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