The language of this verse is hesitant: “But be careful lest perhaps this power of yours….”

The word translated liberty may mean “power,” “authority,” or even “rights”; and “rights as a Christian” is a possible translation too. It is a theme that becomes important in chapter 9, where Paul discusses his own rights as an apostle.

The weak are Christians, as the context makes plain. One may also translate this phrase as “fellow Christians whose faith is weak.”

The word for stumbling block is sometimes used to describe the result that teaching about Jesus has on those who do not accept it (Rom 9.32-33; 1 Peter 2.8). Essentially, though, it means the same as another word for “stumbling block” used in 1 Cor 1.23 (see the comments). The reference was originally to the Old Testament law against making a blind man stumble by putting some object in his path. However, this language was widely used in the New Testament with the wider sense of making someone “fall into sin” (for example, Matt 18.6) or bringing about someone’s spiritual destruction (see verse 11). Some languages cannot speak of “falling into sin.” In such cases one may say “sin by eating such food.”

Quoted with permission from Ellingworth, Paul and Hatton, Howard A. A Handbook on Paul’s First Letter to the Corinthians, 2nd edition. (UBS Handbook Series). New York: UBS, 1985/1994. For this and other handbooks for translators see here .