Nicene and Post-Nicene Fathers: Series II/Volume XI/John Cassian/Against Nestorius/Book VI/Chapter 17

Chapter XVII.

Those who are under an error in one point of the Catholic religion, lose the whole faith, and all the value of the faith.

since this is so, in denying that Jesus Christ the Son of God is one, you have denied everything. For the scheme of the mysteries of the Church and the Catholic faith is such that one who denies one portion of the Sacred Mystery cannot confess the other. For all parts of it are so bound up and united together that one cannot stand without the other and if a man denies one point out of the whole number, it is of no use for him to believe all the others. And so if you deny that the Lord Jesus Christ is God, the result is that in denying the Son of God you deny the Father also. For as St. John says: &#8220;He who hath not the Son hath not the Father; but he who hath the Son hath the Father also.&#8221; By denying then Him who was begotten you deny also Him who begat. By denying also that the Son of God was born in the flesh, you are led also to deny that He was born in the Spirit, for it is the same Person who was born in the flesh who was first born in the Spirit. If you do not believe that He was born in the flesh, the result is that you do not believe that He suffered. If you do not believe in His Passion what remains for you but to deny His resurrection? For faith in one raised springs out of faith in one dead. Nor can the reference to the resurrection keep its place, unless belief in His death has first preceded it. By denying then his Passion and Death, you deny also his resurrection from hell. It follows certainly that you deny His ascension also, for there cannot be the ascension without the resurrection. And if we do not believe that He rose again, we cannot either believe that He ascended: as the Apostle says, &#8220;For He that descended is the same also that ascended.&#8221; Thus, so far as you are concerned, the Lord Jesus Christ did not rise from hell, nor ascend into heaven, nor sit at the right hand of God the Father, nor will He come at that day of judgment which we look for, nor will He judge the quick and the dead.