Romans 14:21-23 meaning

If a fellow believer thinks that it is wrong to consume a particular substance, then we should not participate in that thing around or with that believer: It is good not to eat meat or to drink wine, or to do anything by which your brother stumbles. The faith which you have, have as your own conviction before God. Happy is he who does not condemn himself in what he approves (vv 21-22). 

If we have the faith to eat or drink, but someone else does not, then we should be careful not to lead our brother into sin. This is because when we violate our conscience it is sinful for us: whatever is not from faith is sin (v 24). 

To demonstrate this, Paul uses the example of food and wine. In Paul's day, some food was seen as unclean and thus a food that believers should not partake of. Paul states that even though none of these foods are unclean (Romans 14:14), it is still wrong to eat these foods around believers who think the opposite. 

There are two reasons for this. First, if a believer does something without faith, then they should not do that thing—it would be sinful of them if they did: He who doubts is condemned if he eats, because his eating is not from faith; and whatever is not from faith is sin (v 23). 

Secondly, if there is a weaker believer in the faith who sees something as sin even though it is not declared a sin in the Bible, those believers who are stronger in the faith should not condemn that believer but should instead avoid that thing too.

If doing something hurts the conscience of the Christian who does it, he should give up that action. If doing that same thing does not hurt our conscience, but hurts the conscience of a fellow believer, why would we want to harm them? 

We should, instead, refrain from that action or substance when in the company of the weaker believer. This is so that those stronger in the faith do not tempt their fellow believer to do something apart from their own personal faith (v 23). We do all of this so as to create harmonious and righteous living together as believers, which God has called us to (Romans 12).

When someone violates their conscience, it leads to sin and can lead to their life becoming shipwrecked (Romans 14:23; 1 Timothy 1:19). Paul mentions the word conscience three times in Romans:

• In Romans 2:15, he said Gentiles show that they are made in God's image and therefore reflect God's law "in that they show the work of the Law written in their hearts, their conscience bearing witness."
• In Romans 9:1, Paul appeals to his own conscience as a witness that what he is saying is true.
• In Romans 13:5, Paul asserts that believers should obey governing authorities not only because of the negative consequences that can stem from breaking the law, but also "for conscience' sake." This is because our consciences will judge us when we stand before Jesus at the judgement (Romans 2:16). 

Paul makes frequent mention of his own conscience in his writings. He refers to his conscience as a witness that gives him confidence that he is in the right (2 Corinthians 1:12). However, he also recognizes that just because he is not aware of anything wrong, God is the ultimate judge (1 Corinthians 4:4-5). Paul offers up himself as an example to follow, that he puts the best interest of others above his own freedom to partake in things he might prefer or enjoy:

"just as I also please all men in all things, not seeking my own profit but the profit of the many, so that they may be saved."
(1 Corinthians 10:33)

All this focuses us back on the primary admonition of Romans, to learn to choose a perspective that is real and true, one that sees being a living sacrifice to God is in our best interest (Romans 12:1-2). This is because approaching life in this way allows us to live according to God's design, which Paul calls righteousness. Living this way, by faith, is the opposite of living by pride (Romans 1:16-17; Habakkuk 2:4). When we live in pride, seeking our own way, we inevitable fall into sin and its negative consequences. 

Sin brings death, a separation from living in God's design (Romans 6:23). Living a life that is self-seeking leads to wrath and indignation, but walking in faith brings us honor from God, and the reward of eternal life (Romans 2:6-8). Gaining the gift of eternal life comes simply through faith (Romans 3:1-3; John 3:14-15). But the reward or experience of eternal life depends on the choices we make. Paul exhorts believers to choose to believe that God's ways are for our best, and to adopt a mindset that sees walking in faithful obedience as being the way to gain our greatest benefit. 

Jesus gave the example of learning to adopt such a mindset as choosing the narrow path over the wide path (Matthew 7:13-14). The narrow path looks hard, because it is. It is difficult to obey Jesus's command to take up our cross daily and walk in obedience to Him, enduring rejection and loss from the world (Matthew 16:24). 

But this is the mindset that Jesus chose. And because of choosing this mindset, He was given incredible rewards, even the reward of reigning over the earth. Paul exhorts believers to adopt the same mindset as Jesus (Philippians 2:5-7). He exhorts us to choose the same mindset because Jesus has offered for us to share His inheritance if we suffer as He suffered (Romans 8:17b; Revelation 3:21). 

A part of this mindset is to be sufficiently focused on understanding our fellow believers such that we recognize when they have a weak conscience, and take measures to willingly restrict our own freedom that we might not cause them to stumble.