The Pentecostal movement began in 1901 when students at Bethel Bible College in Topeka, Kansas came to the conclusion that speaking in unknown languages under the power of the Holy Spirit -- called speaking in tongues -- was the initial sign that a believer had been filled with, or baptized in, the Holy Spirit. The Pentecostal movement, which was initially non-denominational, has since become one of the largest groups within Christianity. Today, more than 700 denominations identify with the Pentecostal movement. The largest of these is the Assemblies of God, which formed in 1914.

How to Become Holy

The Assemblies of God holds to some teachings and practices that differ from those of other Pentecostal denominations. Generally, some other Pentecostal denominations agree with the A/G on these points and others disagree. Many Pentecostals, especially early Pentecostals believe that a person must be sanctified -- supernaturally made holy by God -- before he can receive the Holy Spirit. The Assemblies of God teaches that sanctification is a separate but related process that begins when a person receives Jesus Christ as savior and continues until he is completely sanctified in heaven after death. Historically, this teaching was influenced by the many formerly Baptist and Christian and Missionary Alliance ministers who affiliated with the Assemblies of God.

Trinitarianism and Oneness

Shortly before the Assemblies of God formed, the Pentecostal movement experienced one of its first and most significant rifts. About one-third of the new movement accepted a new teaching that Jesus Christ is the entirety of God and that all baptisms should be performed using the phrase "in Jesus' name." This group became known as Apostolic Pentecostals, Oneness Pentecostals or Jesus-Only Pentecostals. Their teachings were in opposition to traditional Christian teachings accepted by other Pentecostals, including the Assemblies of God, that God is a triune being -- called the Trinity -- who has revealed himself in the three distinct yet unified persons of the Father, Son and Holy Spirit. Some people use the term ''Pentecostal'' to refer exclusively to Oneness Pentecostals.

Baptism in Water

The largest Oneness Pentecostal denomination is the United Pentecostal Church. Like other Oneness churches, the UPC teaches that believers must be baptized by immersion in Jesus' name to be forgiven of sin and go to heaven. The Assemblies of God and other Trinitarian Pentecostals also baptize by immersion, but use the traditional baptismal pronouncement "in the name of the Father and of the Son and of the Holy Spirit." The A/G teaches that baptism is symbolic and used to declare to others that a person has become a believer in Christ. They teach that a person's salvation comes from receiving Jesus Christ as savior and is not directly caused by baptism.

Baptism in the Holy Spirit

All Pentecostals believe that speaking in tongues is the initial sign of the baptism in the Holy Spirit. Pentecostals of all stripes also share a belief that the Holy Spirit gives spiritual gifts such as divine healing and prophecy to the church as God wills. The Assemblies of God -- and most other Trinitarian Pentecostals -- believe that the baptism in the Holy Spirit is a separate experience from salvation and that a person can go to heaven without having experienced it. Oneness Pentecostals believe that a person must experience the baptism in the Holy Spirit with the evidence of speaking in tongues to be saved and go to heaven.

Outward Appearance

The most visible difference between Oneness Pentecostals and the Assemblies of God has to do with what Oneness Pentecostals refer to as "holiness standards." Women in Oneness Pentecostal churches are typically expected to wear full length dresses or skirts at all times and to refrain from cutting their hair or wearing makeup and jewelry. Men are expected to cut their hair short and to wear full length pants. The Assemblies of God -- and most Trinitarian Pentecostals -- encourage their members to dress modestly, but generally leave the specifics of modesty to the consciences of individual believers.