Who founded the religion of Christianity and when?

Jesus founded it. The church began 50 days after Jesus' resurrection (c. A.D. 35). Jesus had promised that He would build His church (Matthew 16:18), and with the coming of the Holy Spirit on the day of Pentecost (Acts 2:1-4), the church-ekklesia (the "called-out assembly")-officially began. Three thousand people responded to Peter's sermon that day and chose to follow Christ.