Now this our religion which is called Christian and Catholic is founded chiefly on the following assertions. From all eternity, that is, before the world was established, and so before all that is meant by time began, there has existed one divine substance of Father, Son, and Holy Spirit in such wise that we confess the Father God, the Son God, and the Holy Spirit God, and yet not three Gods but one God. Thus the Father hath the Son, begotten of His substance and coeternal with Himself after a manner that He alone knoweth. Him we confess to be Son in the sense that He is not the same as the Father. Nor has the Father ever been Son, for the human mind must not imagine a divine lineage stretching back into infinity; nor can the Son, being of the same nature in virtue of which He is coeternal with the Father, ever become Father, for the divine lineage must not stretch forward into infinity. But the Holy Spirit is neither Father nor Son, and therefore, albeit of the same divine nature, neither begotten, nor begetting, but proceeding as well from the Father as the Son.[45] Yet what the manner of that Procession is we are no more able to state clearly than is the human mind able to understand the generation of the Son from the substance of the Father. But these articles are laid down for our belief by Old and New Testament. Concerning which fortress and citadel[46] of our religion many men have spoken otherwise and have even impugned it, being moved by human, nay rather by carnal feeling. Arius, for instance, who, while calling the Son God, declares Him to be vastly inferior to the Father and of another substance. The Sabellians also have dared to affirm that there are not three separate Persons but only One, saying that the Father is the same as the Son and the Son the same as the Father and the Holy Spirit the same as the Father and the Son; and so declaring that there is but one divine Person expressed by different names. The Manichaeans, too, who allow two coeternal and contrary principles, do not believe in the Only-begotten Son of God. For they consider it a thought unworthy of God that He should have a Son, since they entertain the very carnal reflection that inasmuch as[47] human generation arises from the mingling of two bodies, it is unworthy to hold a notion of this sort in respect of the divine nature; whereas such a view finds no sanction in the Old Testament and absolutely[48] none in the New. Yea, their error which refuses this notion also refuses the Virgin birth of the Son, because they would not have the God's nature defiled by the man's body. But enough of this for the present; the points will be presented in the proper place as the proper arrangement demands.