However, I think there is some confusion on how this principle applies in other situations, specifically as it deals with those who have differing convictions. What I mean by that is, one person thinks something is permissible for a Christian and the other doesn't. I've seen this come up in a number of scenarios: drinking, gambling, what movies one watches, what constitutes profane language, the extent of our observance of the law of the land (e.g. speed limit, downloading music), and the list continues. In Biblical times food practices and feast days fell into these categories.
As always the question that should guide our thinking and practice here is "what has God said about it in His Word"? Probably the clearest passage answering the present question is Romans 14. I'd encourage you to read the whole thing or at least have it in front of you as you read my comments on it.
First let's identify the stronger and weaker brothers. Notice the passage is talking about brothers, so we are here discussing relationships between Christians. In verse 2 we see that the weaker brother is the one with stronger, or more strict, convictions (in the case of Romans 14, the one who abstains from meat). This brother could be called weaker either because he has not fully embraced his freedom in the gospel to eat whatever he wants or because actions might cause him to stumble that don't cause others to stumble. So if someone is choosing to abstain from something we are not required to abstain from in scripture, they are the weaker brother.
What then should be our attitude towards one another? To put the matter simply, the one who feels freedom to engage in something that the other is abstaining in should not despise the one who abstains, and the one who abstains should not judge the one who doesn't (v. 3). This is because we've both been accepted by God and He is our judge (v. 4). We should each do what we do because we are convinced in our minds it is right, and we should do it as unto the Lord (v. 5-6). We shouldn't abstain or not abstain to please others, but because we feel it is what God has called us to do.
If that describes our attitude, what should our actions look like towards one another? In this section of the passage (v. 13ff), Paul addresses mainly the "stronger" brother. He is the one Paul associates himself with (since Paul feels the freedom to eat any food), and he is the one at risk of being a stumbling block. Paul basically says they should not partake of the thing the weaker brother is abstaining from if they are in close contact with the weaker brother (v. 15-16, 19-20).
The reasons given are:
- so that our conduct will not be spoken of as evil (v. 16)
- the kingdom of God isn't in it (i.e. loving people is a bigger deal than abstaining from these things) (v. 17)
- it is the peaceful and mutually upbuilding option (v. 19)
- if we cause a brother to be tempted towards doing the thing he feels God has called him not do, we are tempting him to act out of step with faith, and anything that does not proceed from faith is sin (v. 23, in other words to do the thing he is abstaining from is "unclean for him" (v. 14))
To my mind this text gives us very clear guidelines in how to approach these issues: For those with the more strict convictions (the abstainers), don't judge those who don't abstain. For those with the looser convictions, don't despise those who do abstain. Futher, don't carry out the action the other abstains from in such a way that they might be tempted to go against their convictions.
A quick example of what I mean: I drink. I believe drunkenness is a sin (cf. Eph. 5:18), but I think God gave alcohol for a good purpose (cf. Psalm 104:15) and when used in moderation it is ok. Hardcore Southern Baptists disagree with me. When I am around them or influencing them in some way scripture commands me to abstain from alcohol so as not to be a stumbling block to them.
A note in closing: I want to be very clear that I don't think everyone in the Christian community agrees with what I've just summarized. I hear much more of something to this effect: "If you abstain from the thing the other person is abstaining from, what you're saying is that we don't have freedom in the gospel. This either supports legalism or at least looks legalistic to non-believers. It is therefore a barrier to the gospel." Given the clarity of Paul's thought in Romans 14, the case is just the opposite. Paul sees NOT abstaining when around an abstainer as the real barrier to the gospel, and Paul is writing under the inspiration of the Holy Spirit.