Epiphanius Ancoratus 6

How are you able to be so reckless to say that the Father was not always the Father and, even more recklessly, also say the Son did not exist? If you do not have the backbone to give any value to the Father (for his identity and Being is always in the ground of His existence, with no need for additions, no additional glory and no additional advance). Learn not to blaspheme. To those who fight against the faith, it would be far better you run away from the faith! Nonetheless, you must always trust the eternal Father truly has begotten the Son, the One who truly exists who is with the Father, who truly exists. There is no fusion into the Father’s Being, nor is He a brother of the Father but He is truly the genuine Son, Begotten from out of the Father, His natural Son, not adopted. The Son is of the same Being with the Father, not sharing the Father’s Being, but of the same Being and not Begotten apart from the Father as some might hold in their private thoughts with their thinking the Son is adopted and not in truth. To say “of the same Being” is the bond of faith. If you say “of the same Being,” you destroy the power of Sabellius. Whenever we say “of the same Being,” it signifies one “Person” but it indicates the Person of the Father “mutually indwells” and the Person of the Son “mutually indwells” and the Person of the Holy Spirit “mutually indwells”. Whenever someone says “of the same Being,” does not signify the Son is foreign to the Godhead but shows the Son is “God from God” and the Holy Spirit is also God together in the Godhead, not three Gods. We are not talking about “two gods’ when we say the Father and the Son are God, for our God is “one.” As Moses would happily say: “The Lord your God, the Lord is one” (Deut. 6.4). We do not say god’s. God the Father, God the Son, God the Holy Spirit and “not god’s.” There is no polytheism in God. By means of the three names there is one divine nature, Father and Son and Holy Spirit. There are not two sons for the one Son is the Only-Begotten and the Holy Spirit, the Spirit who is Holy, the Spirit of God, always with the Father and the Son, not foreign from God but from God, who proceeds from the Father, and is receiving from the Son. But the Only-Begotten Son is beyond comprehension, and the Spirit is beyond comprehension but from God and not foreign from the Father and Son. The Trinity always existing and consisting in the same Being.  There is no different Being alongside the Godhead and there is no different Godhead alongside the Being. The Son and the Holy Spirit are the same Godhead and come from out of the same Godhead.