Why did Paul say it wasn't a sin to eat meat sacrificed to idols when the other apostles and even jesus said it was?

This is a quote/extract from an official letter (verses 23-29) written by the apostles and elders in Jerusalem (the first church council) to new (gentile) believers in various districts. James suggested this particular content (v 13, 20). His recommendation was wholeheartedly endorsed by all the Apostles, and by the church Elders, and by the entire congregation there (v22).

The Council then decided that this policy be formally written up and issued as a decree and taken to various other congregations by selected and trusted congregation members. Paul, Barnabus and Silas are named as being included in that group.

Many years later, in Paul's subsequent letter to the Corinthians, 1 Cor ch 8:v1-8, he specifically addresses issues of foods/things offered to idols, and by kind and skillful argumentation, and under the direction of the holy spirit, provides further considerations to guide the Christian conscience on issues relating to food and idol worship.

The thrust of his argument in 1 Corinthians 8 remains consistent with the decree of Jerusalem, but also provides additional guidance and principles that help believers in other, yet related, aspects of Christian living. In chapter 10 he again exhorts believers to avoid idolatry, and includes counsel with reference to the prevalence of 'pagan' (and 'sacrificial') food being sold there in Corinth's meat markets (ma′kel·lon). Corinth was an ancient and prominent Greek city, famous for its temple to Aphrodite and for its temples to many other gods and goddesses. Votive offerings to these gods were common practice. In such circumstances it is understandable why Paul continued to emphasise the Christian position, i.e. to avoid idolatry. He provided the Christians in Corinth with practical guidelines, and always stressed the importance of (a) avoiding idolatry, and (b) using an informed conscience on matters of Christian decision making.

*NOTE: 'meats offered to idols' is the phrase the King James Version (KJV) uses to translate into English the one Greek Word eidolothyton, which means (something) sacrificed to idols. Eidolothyton is translated as 'things sacrificed to idols' in the Douay-Rheims Bible, Webster's Bible, New American Standard Bible etc.