Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The United Pentecostal Church International (UPCI) is a Pentecostal Christian denomination, headquartered in the St. Louis suburb of Hazelwood, Missouri. It is a part of the Oneness or Apostolic portion of the Pentecostal Movement, and was formed in 1945 by a merger of the former Pentecostal Church, Incorporated and the Pentecostal Assemblies of Jesus Christ. This church is especially distinguished by its adherence to Oneness theology, its use of baptism in Jesus' name (as opposed to the Trinitarian formula), and an emphasis upon Holiness living in all aspects of one's life. The UPCI emerged out of the Pentecostal Movement, which traces its origins to the teachings of Charles Parham in Topeka, Kansas and the Azuza Street Revival led by William J. Seymour in 1906. Rejected by the mainline churches, Pentecostals began to form organizations of their own. One of these new groups was the Assemblies of God, which formed in 1914.