What does Romans 14:7 mean?

This verse must be read and understood in the context of the verse that follows. Paul has insisted that whatever side someone is on in one of the disputed matters in the early church, each person should be fully convinced of his or her position and participate (or not) to honor the Lord. Strictly speaking, those who associate sin with things God has not explicitly condemned are considered those "weak in faith" (Romans 14:1). However, those who embrace their Christian freedom in that are not to look down on those who are more convicted. And, those with more restrictive opinions should not judge those who don't share their view (Romans 14:3). Christians ultimately answer to God, not to each other (Romans 14:4; Colossians 2:16–23).

Now Paul writes that no one lives or dies to themselves. Christians are not meant to exist in a vacuum. In fact, we cannot wall ourselves off from the Lord or other believers. Whatever we do, we belong the Lord. That's what Paul will declare in the following verse.

In other words, we should not think that our decision about whether to participate in disputed issues is only about us. The Lord is always involved because we are His. That means that only God has the right to judge those issues, but it also means nobody has the right to make decisions on those topics without considering the will of God.