In the Christian religion, Oneness Pentecostalism refers to a certain belief about the nature of the Trinity, Father, Son, and Holy Spirit.
Adherents argue that the Father, Son, and Holy Spirit, aren't three separate persons - as orthodox Christianity contends - but three different manifestations of the same person. It is held that the Father became the Son, Jesus Christ, and the Son became the Holy Spirit.
Oneness Pentecostals sometimes gather together with others like-minded for church, but other times they attend orthodox Christian churches. Advocates of this doctrine, like T.D. Jakes, have been criticized for not being more transparent about their unique beliefs about the nature of the Trinity and pressed about why they try to hide their convictions and mislead Christians about this topic.
History
In the decade between Charles Parham’s ministry and the formal organization of the Assemblies of God, a new doctrine arose in some churches outside Los Angeles, California. Its primary advocate, R.E. McAlister, called it a “new revelation.”
The new teaching emphasized that the New Testament apostles baptized people in the name of Jesus only, and not in the name of the Father or the Holy Spirit. Oneness Pentecostalism, also called “Jesus Only,” “The Name,” Pentecostal Unitarianism,” and the “New Issue,” spread quickly on the West Coast in the early 20th century. Adherents were re-baptized with the new verbal formula “in the name of Jesus only.”
The new revelation was considered unorthodox by most Pentecostals because it denies central tenets of the Trinity by claiming that the Father, Son, and Holy Spirit are the same person and not distinct persons. Oneness Pentecostals further held that if someone was baptized in Jesus name, and didn’t immediately speak in tongues, then they weren’t a Christian.
Certain Californian ministers such as Frank J. Ewart and Glenn Cook were re-baptized with the new formula and then convinced many Pentecostals to do likewise when they traveled east to spread their message to other Pentecostal Americans.
Their influence caused panic in the budding Assemblies of God movement in the south. Rumors spread that the entire presbytery of the Assemblies of God had been re-baptized. Assemblies of God publications began printing articles defending the orthodox understanding of the Trinity, calling Oneness Pentecostalism "Modalism," which was a teaching the Christian church had deemed heretical in previous centuries.
When the 16 Fundamental Truths were articulated in 1916, they reflected an orthodox teaching of the Trinity and water baptism.