Paul calls his readers to an alternative approach to passing judgement on one another. The alternative way is to decide to not do anything that would hinder another Christian. Basically this is an example of putting others above yourself, so it is an expression of brotherly love.
What is Paul referring to here by stumbling block or hindrance? He does not have in mind the cessation of a sinful activity because a Christian should never engage in sinful activity. Nor is he referring to something that a believer has been commanded to do by the Bible because a Christian should never use the feelings of someone else as a reason for disobeying a commandment of God. Instead Paul has in mind the wide range of attitudes and activities that come under the idea of Christian liberty.
What is this decision based on? It is based on what Jesus taught and it is connected to what another believer regards as important. Paul uses the example of food. The Old Testament ceremonial law said that certain foods were unclean. Paul knew that Jesus had abrogated those requirements and that he, although a Jew, was now under no obligation to conform to those laws. Yet he also knew that some weak believers still imagined that those foods were unclean and could be grieved if they saw a believer eating them. So while he was not willing to change his convictions, he was prepared to adjust his practices.
What am I like if I cause grief to another believer? Paul says that the Christian who ignores the feelings of his fellow believer is not walking in love. What does it mean to walk in love? Paul tells us in Ephesians 5:2: ‘And walk in love, as Christ loved us and gave himself up for us, a fragrant offering and sacrifice to God.’ To walk in love is to behave sacrificially and not selfishly. It is to go without what I would like in order to benefit my fellow Christian.
What will happen if I insist I am free to eat? I will destroy my fellow-believer, described here as ‘the one for whom Christ died’. ‘Destroy’ is obviously a strong term, and is used again in verse 20, but what does it mean? I suppose it could mean that we could cause someone to give up the faith or we could cause someone to obey us rather than God or we could cause someone to become so downcast that they become spiritually ineffective. Whatever the meaning is, to ignore it can never be an expression of brotherly love.
What will others think if I claim my freedom? We can imagine the situation. A Christian is found in great distress. Those who found the distressed Christian will say of me, ‘His behaviour is not brotherly; instead it is sinful.’ So what I knew to be good – freedom to eat an unclean food – is now regarded as evil because it is the cause of another Christian’s distress.
Of course, we can respond to the weak brother and say about him, ‘Surely he should learn what the Bible says.’ That is true, and no doubt Paul would agree with that suggestion. Yet what Paul is speaking about here is how other believers react to the weak brother until he gets to the stage where he becomes a mature believer who has grasped what the Bible says. We can’t avoid noticing that part of being a living sacrifice is to live sacrificially and not selfishly.