Why did the Jews oppose Paul's ministry to the Gentiles?
The Jews opposed Paul's ministry to the Gentiles because, once God began calling out a predominantly Gentile people for His name—the church, which is His body—they became envious. That envy led them to oppose Paul everywhere he went, and God then placed a national blindness upon Israel.
Les explains that after Peter recounted how God first visited the Gentiles at the house of Cornelius, James said God was taking out of the Gentiles a people for His name—the church, which is His body. For over 1900 years now, the church has been formed predominantly by Gentiles called out from whatever they were, pagans or otherwise, and becoming members of the Body of Christ. As soon as that began, the Jews got envious and began to oppose Paul's ministry everywhere he went. God then put a blindness upon the nation. But Les reminds people that God deals with the Jew on two levels, national and personal; when He blinds them nationally, that does not take away the personal opportunity for salvation.