How do I know if something is a sin?

Question 11088

For many things in Christian life, this question has a straightforward answer: Scripture names them, and that settles it. But there is a genuine and growing category of situations, particularly in contemporary life, where the specific action is not mentioned in the Bible and where Christians may hold quite different views. How do you navigate that territory without either the paralysis of treating everything as potentially sinful or the carelessness of dismissing anything that is not explicitly named?

Start With What Scripture Explicitly Says

The most important step is to actually know what Scripture says. A significant portion of what Christians wonder about has, in fact, been addressed by God’s word, and the answer is that it is sin. The works of the flesh in Galatians 5:19–21 are direct and specific: sexual immorality, impurity, sensuality, idolatry, sorcery, enmity, strife, jealousy, fits of anger, rivalries, dissensions, divisions, envy, drunkenness, and carousing. Colossians 3:5 and 8 add covetousness, bitterness, wrath, malice, slander, and obscene talk. The Ten Commandments in Exodus 20 address the fundamental categories of sin against God and against neighbour. Jesus’ summary in Matthew 22:37–40 states the governing principle underlying all of them: love God with everything you have and love your neighbour as yourself.

Before reaching for more nuanced tests, it is worth asking whether Scripture has already answered the question. Many situations that feel grey are not actually grey; they are simply uncomfortable to acknowledge as sin because they are familiar, or because confronting them would be costly.

The Conscience Test

Romans 14:23 contains a statement with wide application: “whatever is not from faith is sin.” Paul’s immediate context is the disagreement between believers over food offered to idols, but the principle he applies has broader reach. If you cannot engage in something with a settled conscience before God, if doing it requires suppressing an inner conviction that something is wrong, that inner conviction deserves to be taken seriously. The Holy Spirit uses the conscience as an instrument, and an uneasy conscience about a specific action is worth examining rather than overriding.

The conscience is, however, not infallible. It can be too tender in some areas and too hardened in others. It can be shaped by cultural background, upbringing, or legalistic teaching in ways that produce unnecessary guilt about things that are genuinely not sinful. So the conscience is a signal to investigate, not a verdict to accept without examination.

The Enslavement Test

1 Corinthians 6:12 gives Paul’s way of thinking about things that may be permissible in themselves: “All things are lawful for me, but not all things are helpful. All things are lawful for me, but I will not be dominated by anything.” The question here is not merely “is this sinful?” but “is this getting a grip on me?” If something is consuming disproportionate time, energy, or thought, if the prospect of giving it up produces genuine resistance or anxiety, if it is slowly shaping priorities and decisions in ways that displace God, it has moved from permissible activity into a functional idolatry. That is a sin regardless of whether the specific thing is explicitly named.

The Love Test

Romans 13:9–10 draws together the relational commandments and concludes that “love is the fulfilling of the law.” The question “does this harm my neighbour?” is not a secondary consideration but a fundamental one. An action that injures, demeans, exploits, or diminishes another person violates the law of love and is therefore sinful regardless of whether it is otherwise technically permissible. James 4:17 adds the category of omission: “whoever knows the right thing to do and fails to do it, for him it is sin.” Sin is not only doing what is forbidden; it is also failing to do what love requires.

The Glory Test

1 Corinthians 10:31 provides an overarching principle: “So, whether you eat or drink, or whatever you do, do all to the glory of God.” The question is not only “is this prohibited?” but “can I do this in a way that honours God?” If an action is genuinely incompatible with the conscious awareness of being in God’s presence, if you would not do it in a room where you were visibly before God, that incompatibility is worth taking seriously. This is not about artificial performance or self-consciousness; it is about the integrated life in which everything is done as before God.

So, now what?

These tests work together rather than in isolation. A wise and honest application of all of them, in a heart that genuinely wants to please God and is open to the Spirit’s conviction, will navigate most genuinely grey areas with integrity. The person who is asking “how do I know if something is a sin?” with a sincere desire to honour God is already most of the way to the answer, because that desire itself comes from the Spirit and is exactly what he is working to produce and strengthen.

“So, whether you eat or drink, or whatever you do, do all to the glory of God.” 1 Corinthians 10:31