[3]The baptisms of those to be received into the Catholic Church from other Christian communities are held to be valid if administered using the Trinitarian formula.
In case of necessity, anyone, even a non-baptized person, with the required intention, can baptize, by using the Trinitarian baptismal formula.
[7] Greek Orthodox practice changed in 1755, when Patriarch Cyril V of Constantinople issued the Definition of the Holy Church of Christ Defending the Holy Baptism Given from God, and Spitting upon the Baptisms of the Heretics Which Are Otherwise Administered; however, the Greek Orthodox do not currently insist on re-baptizing Catholics.
[8] The Reformed Churches teach that "The sacrament of baptism is but once to be administered unto any person" (Westminster Confession of Faith Chapter 28, Paragraph 7).
[9] As such, an individual who was baptized using the Trinitarian formula in a Nicene Christian denomination can be received into the Reformed Church through a profession of faith.
[10] Anabaptists believe that baptism is only valid once the recipient has full faith in Christ and requests to be baptized.
[11] Latter Day Saints practice rebaptism, as they believe that the priesthood authority to perform baptisms resides in their church only.