Original sentence: Semi-Arianism was a position regarding the Trinity adopted by some 4th century Christians.Though it modified the teachings of Arianism it still rejected the doctrine that Father, Son, and Holy Spirit are of the same substance and was consequentially considered to be heretical by many contemporary Christians
Edited sentence: Semi-Arianism is considered to be a 4th-century Trinitarian heresy in the Christian church.Though it modified the extreme position of Arianism, it still fell short of the church's orthodox teaching that Father, Son, and Holy Spirit are of the same substance