What are gray issues in Christianity?

from the old testament

• Scripture is not meant to reveal or provide instruction for everything, but what it has revealed, we are to faithfully obey (Deuteronomy 29:29). When it comes to “gray” issues—those not explicitly answered by Scripture—a believer is to strive to come to an answer based on Scripture’s teaching. All of the Old Testament provides such wisdom through example and explanation, with Proverbs being particularly helpful for general wisdom on how fearing the LORD (Proverbs 1:7) looks in practice.

from the new testament

• Second Timothy 3:16–17 reads, “All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness, that the man of God may be complete, equipped for every good work.” It teaches that Scripture is sufficient for life—it is all a believer needs to honor God.
• However, being sufficient doesn’t mean it’s comprehensive in the sense of giving explicit answers for every situation. A “gray” issue is one on which it doesn’t provide direct answers. This contrasts with “black and white” issues, such as lying (Colossians 3:9), where Scripture provides direct teaching.
• Believers can apply Scripture to “gray” issues by first understanding what the original author meant in a passage and what the original audience would have understood him to be saying. They then “bring that forward” by following the trajectory of that application to their current situation.
• Doing all of that requires patience and careful study. Also, for “gray” issues, often multiple passages need to be considered at once to get a fuller application. Because of the work involved and the complexities of some questions, believers will often reach different conclusions about the same question. There are many reasons for this, including the fact that we are still affected by sin (Romans 7:18; 1 John 1:8, 10), have different backgrounds (Romans 14:2–3), and even different levels of maturity (Hebrews 5:14).
• Note that a “gray” issue is different than a secondary or primary issue.  A primary issue is any divergence from core doctrines, which creates a division between genuine and false believers such as the belief that salvation is by grace or by works. A secondary issue is a difference of view that divides true believers while they can still be believers, such as views on how to understand Scripture in terms of covenants vs dispensations. Those issues are between genuine believers but are more distinct than “gray” ones.Conversely, a “gray” issue is known as a “tertiary” issue because it’s small, and differences between believers should not lead to separating into different churches, as with secondary issues, nor to accusing others of being unbelievers, as with a primary issue.
• However, though gray issues are “tertiary,” strongly held convictions can lead to friction among believers in the same local church body. Regarding such issues, Paul said, “Do nothing from selfish ambition or conceit, but in humility count others more significant than yourselves” (Philippians 2:3). Believers are to think about others first.
• This is true even if it means giving up what we are free to do when it causes other believers to stumble. Speaking about those who had problem with eating meat sacrificed to idols, Paul said, “if food makes my brother stumble, I will never eat meat, lest I make my brother stumble” (1 Corinthians 8:13). He was saying that even though he came to the biblically informed conclusion that eating such meat was not sinful, because others came to the different conclusion that it was, he was willing to give up meat rather than cause friction with the other believers.

implications for today

The Christian life is about knowing God and Jesus more as Scripture presents Him and then applying that biblically grounded wisdom to all aspects of life. Gray issues arise when Scripture doesn’t speak directly to a particular situation. To illustrate how gray issues look in real life, let’s use the common example of whether one should homeschool their kids or send them to public school.

Scripture does address education, specifically that parents are to be the primary teachers of their children about God and Jesus (Deuteronomy 6:6–7). However, when it comes to other subjects such as math, biology, and so forth, the Bible is silent. Believers thus arrive at various conclusions based on many factors, including the expense of homeschooling (one parent leaving the workforce), concerns about the secular influence on their children’s minds, and even their own comfort level with teaching higher-level subjects. The result is that the answer is tailored to each family and might be the best available, not necessarily the one they desire. Unfortunately, sometimes believers elevate educational decisions to the level of a demonstration of one’s spiritual maturity. Some even go so far as to doubt one’s salvation if another family doesn’t educate in the same manner.

However, gray issues are gray because Scripture doesn’t always give black-and-white answers, leaving one to navigate the many influencing factors as wisely as they can while balancing Scripture-derived wisdom with the realities of the life God has given them. Because of this difficulty, one believer must never judge or question another believer’s conclusion. We are saved through Christ’s work, not through, in this example, our schooling choices. We may later decide our previous decision wasn't the best and adjust, but ultimately, gray issues are gray because their answers are unclear.