Pentecostal research papers show that the Pentecostal churches--sometimes called Assemblies of God--are the fastest growing branch of any component of Christianity. Given the “indistinct nature of many Pentecostal groups and the vast number of names and organizations, it is difficult to recognize all Pentecostals… However, … the world-wide total of Pentecostals is estimated at claiming close to one hundred million adherents,” [Brown, Pentecostalism] with some estimates running considerably higher.
While in doctrinal terms Pentecostal churches are often similar to fundamentalist groups (e.g., Baptists), it is the belief in the manifestation of the Holy Spirit in the individual that separates Pentecostals from other Christian churches. While the first Pentecostal churches were founded in the United States at the beginning of the 20th century, Pentecostalism has roots extending back to late 18th century England. There were a number of contributors. John Fletcher and the “second blessing”: Fletcher (Jean de la Flechere) was a Swiss Calvinist theologian and close associate of the founders of Methodism, John and Charles Wesley. In his tract, A Plain Account of Christian Perfection (1766), John Wesley posited the possibility of “entire sanctification” (sometimes called “perfect love” or “Christian perfection”). It was this “second blessing” that Fletcher called a “baptism of the Holy Spirit,” which brought both spiritual power and cleansing. While many Methodists claimed to have undergone this experience in ensuing years, there was, as yet, no connection with speaking in tongues or any other charismata.