Before Peter could preach the gospel to the Gentile Cornelius and those in his house, the Holy Spirit had to prepare Peter to preach the gospel to the Gentiles. For Peter to try to add Gentiles to the church would not be received well by the Judaizing Christians that inhabited the church. However, since the Holy Spirit told Cornelius to send his men to get Peter, that same Holy Spirit had to prepare Peter to go to Cornelius to preach.