Do I have to worry about eating meat that an idolater believes was sacrificed to a pagan god to keep demons away?
No, a believer need not worry about eating meat an idolater believes was sacrificed to a pagan god to keep demons away. Those idolatrous gods cannot do anything to you because you are a believer, so go ahead and eat without worry. But if your eating would cause a young, immature believer to stumble, then don't eat it.
Les explains that Paul never told believers to stay away from a pagan wedding feast; they were free to go. Even though the idolater friend believed the meat had to be blessed and sacrificed to a pagan god to keep demons out, the believer did not have to worry. Those idolatrous gods could do nothing to a believer. So the instruction was: go ahead and eat the meat and don't worry. Yet Paul also balanced this with concern for a brand-new Christian at the same table who had no maturity. If the mature believer's eating would cause that young believer to stumble, then he should not eat the meat. The idol itself had no power. Les also notes that pagan temple priests kept a portion of the sacrificed meat, much like Israel did, and returned the rest to the individual.