In this way, the Church of Christ that struggled for the triumph of Orthodoxy against heresy came to be called the Orthodox Church. This accentuates the fact that it is the lawful inheritor and faithful protector—both in letter and in spirit—of the true teachings of Christ and the Apostles; i.e., of the Orthodox faith, elucidated by the Holy Fathers and confirmed by the Seven Œcumenical Synods. Since the truth is only one, just as only one straight line connects two points—man and God—, all other religious communities, which have deviated from the Orthodox Church of Christ, must not be called “Orthodox,” but should be characterized as “heterodox” (“thinking differently”), by virtue of having distorted the Gospel of Christ and joined to it “another gospel” (see Galatians 1:6). Such is the confession of the Roman Catholics, who fell away from Orthodoxy, initially, because of the arbitrary act of adding the expression “and from the Son” (Filioque) to the eighth article of the Nicæan-Constantinopolitan Symbol of Faith (Creed) and, later, on account of a number of innovations of more or less importance, introduced throughout the centuries and even up to our own time.