1 Corinthians 10:18 - Matthew Poole's English Annotations on the Holy Bible

Israel after the flesh was the whole seed of Jacob, the whole body of the Jewish church; for believers only were Israelites after the Spirit, Romans 11:6, called the Israel of God, Galatians 6:16. Are not they which eat of the sacrifices partakers of the altar? If in the Jewish church any persons ate of the flesh of sacrifices offered upon God's altar, did they not by that act manifest that they were members of the Jewish church, and owned that God to whom those sacrifices were offered, and that way of worship by which God was so worshipped? By the same reason these Corinthians eating of the flesh of those beasts in the idol's temple, which had been offered unto idols, did by that act declare their owning of the idol, and that idolatrous worship which had been there performed, and were really partakers of the idolatrous altar.