Christians may make a fellow believer stumble if they encourage the believer to do something they believe is sinful. In spiritually neutral matters, Christians should respect each other’s consciences.
The Bible teaches us to put others before ourselves. Even much of the Mosaic Law is rooted in that idea. In the Law God gave to the Israelites, He presents, in specific detail, how they were to treat each other and foreigners who came to live among them (Exodus 22:21). The Law forbade them from actions that would show a lack of love or respect toward others (Leviticus 19:9–10, 14; Deuteronomy 15:7–8; 24:14–15). The suggestion is that as God loves us, we should love others. Believers are not to act in ways that would cause others to literally or figuratively stumble. Jesus reiterates the importance of behavior that shows the love of God and love of others (Matthew 7:12; 22:37–40; Mark 12:29–31; Luke 10:27). Paul’s letters to the Romans and the Corinthians include admonitions about not acting in ways that would threaten a fellow believer’s conscience (Romans 14:21; 1 Corinthians 8:13). The idea in those passages isn’t about accepting sin, which we’re not to do (Galatians 6:1; James 5:19–20). Where sin isn’t an issue, we’re to respect a fellow believer’s conscience. Christians are to be salt and light and seek to not be stumbling blocks (Matthew 5:13–16).
God wants us to think about others, not just ourselves (Matthew 7:12; 22:37–40; Mark 12:29–31; Luke 10:27). For instance, maybe you regularly have a glass of wine with dinner. That’s fine and is your right, legally and biblically, but would it be acceptable for you to open a bottle of wine in front of a believer who has struggled with alcoholism? Or even a brother or sister who doesn’t believe in drinking? No. It’s more loving to recognize that person’s vulnerability and curtail your drinking while around him or her. Or maybe a recent convert at church doesn’t make an effort to introduce herself or strike up a conversation with others. Your first reaction might be to think, “Why should I talk to her if she doesn’t make an effort to talk to anybody?” That’s the reaction of the “natural man” (1 Corinthians 2:14) and may be a stumbling block if that person feels unwelcome. The reaction of a loving Christian is to put pride aside and approach that person in fellowship—even if you take the initiative every week. Our goal should be to show love to others. Some believers may need to be handled with more discernment than others. While we have spiritual freedom in many matters, we must always consider how our behavior affects others. Christians are to be salt and light, not a stumbling block (Matthew 5:13–16).