As a result of Peter's speech on Pentecost day, many Jewish souls joined Christianity. In his speech, Peter explained to the Jews that the events they had witnessed, including the speaking in tongues by the disciples, were the fulfillment of prophecies by the prophet Joel. He also proclaimed the message of salvation through faith in Jesus Christ, and the listeners were convicted and asked what they should do. Peter urged them to repent and be baptized in the name of Jesus Christ for the forgiveness of their sins, and about three thousand people were added to the new Christian community that day. Therefore, the correct option is "many Jewish souls joined Christianity".