1. Apostle in his letter to the Ephesians, reviewing in its manifold aspects the full and perfect mystery of the Gospel, mingles with other instructions in the knowledge of God the following: As ye also were called in one hope of your calling; One Lord, one faith, one baptism, one God and Father of all, and through all, and in us all. He does not leave us in the vague and misleading paths of an indefinite teaching, or abandon us to the shifting fancies of imagination, but limits the unimpeded license of intellect and desire by the appointment of restraining barriers. He gives us no opportunity to be wise beyond what he preached, but defines in exact and precise language the faith fixed for all time, that there may be no excuse for instability of belief. He declares one faith, as he preaches one Lord, and pronounces one baptism, as he declares one faith of one Lord, that as there is one faith of one Lord, so there may be one baptism of one faith in one Lord. And since the whole mystery of the baptism and the faith is not only in one Lord, but also in one God, he completes the consummation of our hope by the confession of one God. The one baptism and the one faith are of one God, as they are of one Lord. Lord and God are each one, not by union of person but by distinction of properties: for, on the one hand, it is the property of Each to be one, whether of the Father in His Fatherhood, or of the Son in His Sonship, and on the other hand, that property of individuality, which Each possesses, constitutes for Each the mystery of His union with the Other. Thus the one Lord Christ cannot take away from God the Father His Lordship, or the one God the Father deny to the one Lord Christ His Godhead. If, because God is one, Christ is not also by nature divine, then we cannot allow that the one God is Lord, because there is one Lord Christ: that is, on the supposition that by their oneness’ is signified not the mystery, but an exclusive unity. So there is one baptism and one faith of one Lord, as of one God.
2. But how can it be any longer one faith, if it does not steadfastly and sincerely confess one Lord and one God the Father: and how can the faith which is not one faith confess one Lord and one God the Father? Further, how can the faith be one, when its preachers are so at variance? One comes teaching that the Lord Jesus Christ, being in the weakness of our nature, groaned with anguish when the nails pierced His hands, that He lost the virtue of His own power and nature, and shrank shuddering from the death which threatened Him. Another even denies the cardinal doctrine of the Generation and pronounces Him a creature. Another will call Him, but not think Him, God on the ground that religion allows us to speak of more Gods than One, but He, Whom we recognise as God, must be conscious of sharing the divine nature. Again, how can Christ the Lord be one, when some say that as God He feels no pain, others make Him weak and fearful: to some He is God in name, to others God in nature: to some the Son by Generation, to others the Son by appellation? And if this is so, how can God the Father be one in the faith, when to some He is Father by His authority, to others Father by generation, in the sense that God is Father of the universe?
And yet, who will deny that whatever is not the one faith, is not faith at all? For in the one faith there is one Lord Christ, and God the Father is one. But the one Lord Jesus Christ is not one in the truth of the confession, as well as in name, unless He is Son, unless He is God, unless He is unchangeable, unless His Sonship and His Godhead have been eternally present in Him. He who preaches Christ other than He is, that is, other than Son and God, preaches another Christ. Nor is he in the one faith of the one baptism, for in the teaching of the Apostle the one faith is the faith of that one baptism, in which the one Lord is Christ, the Son of God Who is also God.
3. Yet it cannot be denied that Christ was Christ. It cannot be that He was incognisable to mankind. The books of the prophets have set their seal upon Him: the fulness of the times, which waxes daily, witnesses of Him: by the working of wonders the tombs of Apostles and Martyrs proclaim Him: the power of His name reveals Him: the unclean spirits confess Him, and the devils howling in their torment call aloud His name. In all we see the dispensation of His power. But our faith must preach Him as He is, namely, one Lord not in name but in confession, in one faith of one baptism: for on our faith in one Lord Christ depends our confession of one God the Father.