Baptismal formula

The trinitarian formula is the phrase "in the name of the Father, and of the Son, and of the Holy Spirit" (original Greek εἰς τὸ ὄνομα τοῦ Πατρὸς καὶ τοῦ Υἱοῦ καὶ τοῦ Ἁγίου Πνεύματος, eis to onoma tou Patros kai tou Huiou kai tou Hagiou Pneumatos, or in Latin in nomine Patris et Filii et Spiritus Sancti), or words to that form and effect referring to the three persons of the Christian Trinity. It is often followed by an "Amen".

These words are quoted from a command of the risen Jesus in the Great Commission: "Go, therefore, and make disciples of all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit" (Matthew 28:19); a small minority of other translations read, "into the name".

According to the doctrines of Roman Catholicism, Eastern Orthodoxy, Anglicanism and most forms of Protestantism, a baptism is not valid if the Trinitarian formula is not used in the administration of that sacrament. Consequently, they may not recognize religious communities that baptize without this formula – e.g. Unitarians, Branhamists, Frankists, Jehovah's Witnesses, and Oneness Pentecostals, all of whom deny the Trinity – as Christian religions. This is also the case with baptisms within The Church of Jesus Christ of Latter-day Saints (LDS church). Although LDS members baptize with the same Trinitarian formula, they reject the Nicene Trinitarian conception and regard the three Persons of the Trinity as being distinct personages united not in substance, but in dominion and purpose. Other faiths (Frankists, Oneness Pentecostals and Branhamists in particular) use the formula "In the name of Jesus Christ" (based on Acts 2:38) for baptism, and in turn re-baptize converts who were first baptized under the Trinitarian formula, sometimes claiming that such persons would not have been previously aware that "Jesus is the Lord".

...
Wikipedia