John Calvin Commentary Acts 21:25

"But as touching the Gentiles that have believed, we wrote, giving judgment that they should keep themselves from things sacrificed to idols, and from blood, and from what is strangled, and from fornication." — Acts 21:25 (ASV)

And as concerning those which have believed. They add this to prevent being thought to be attempting to take away or revoke the liberty they had granted to the Gentiles, because such an action would burden the Gentiles with some prejudice. But, meanwhile, they seem to keep the Jews in bondage, from which they explicitly set free only the Gentiles.

I answer that since the situation of all was the same, similar liberty was granted to both. However, mention is made of the Jews, who were so devoted to their observations and ceremonies that they would not avail themselves of that liberty which they could rightly claim.

But the apostles specifically provided for the Gentiles, so that the Jews, following their usual custom, would not reject them as profane and unclean, because they were neither circumcised nor educated in the worship of the law.

Moreover, to avoid loading the paper with an unnecessary repetition, let readers refer to the fifteenth chapter (Acts 15:20), where they will find those things that pertain to the explanation of this decree.