Does the instruction to avoid causing a weaker believer to stumble apply only to meat sacrificed to idols, or to other areas of life too?
The instruction is not limited to meat sacrificed to idols. It carries into every aspect of life, so anything that causes a weaker believer to stumble should be set aside. The underlying principle is that whether eating, drinking, or whatever we do, all is done for God's glory and without offense.
Les explains that this principle is carried into every aspect of life, not just meat offered to idols. Anything that causes a weaker believer to stumble should be set aside for goodness' sake. He then points to verse 31 as the crux of the matter: whether you eat, drink, or whatsoever you do, do it all for the glory of God. Even ordinary, mundane experiences count if done as unto the Lord. Verse 32 adds the admonition to give no offense to the Jew, the Gentile, or the house of God. Les notes this divides Corinth's population into three categories rather than only saved and lost, because the Jew was still a factor in Paul's day.