Had Peter already become a believer in Jesus before his vision in Acts 10?
Yes, Peter had already believed Jesus was the Christ, repented, and been baptized before the vision. He was a typical Jewish believer still practicing the law and unaware of the doctrines of grace, so he had not yet understood the full implications of grace.
Les teaches that Peter was a Jew who had believed Jesus was indeed the Christ. He had no doubt repented of his sin and been baptized, making him the typical Jewish believer. However, Peter was not yet aware of the doctrines of grace and was still much aware of the law. He had not been told to stop temple worship or that he was no longer under the law. Thus, when the voice told him to rise, kill, and eat, Peter responded that he had never eaten anything common or unclean and was not about to. Les points out that Peter was not mixing law and grace; he simply had not yet received the revelation of grace that the vision would bring.
More Questions
At what point did the Holy Spirit come on the Gentiles in Acts 10?
In Acts 10, the order was totally reversed for the Gentiles: the Holy Spirit was already being evidenced before Peter had finished preaching, before they were baptized, and before he heard their repentance.
Where was Paul when Peter preached to Cornelius in Acts 10?
While the newly converted Paul was in the desert for three years, God was simultaneously starting his outreach to Gentiles by bringing Peter to Cornelius in Caesarea.