What does Eastern Orthodox Christians mean that the Father is the one God?
I understand that Eastern Orthodox Trinitarianism differs from Unitarianism in that the former teaches three divine persons of the same substance (ομοουσιος).
Why is it that the "one God" is numerically identical to the Father?
Why don't Eastern Orthodox Christians also confess that the three persons - the Father, Son and Holy Spirit - together "are one God" like the Athanasian Creed does?
Why do Eastern Orthodox Christians do not call the Son "one God" if he is "of the same substance with the Father" as the Nicene Creed says?
What does Eastern Orthodoxy mean that the Father alone is the one God?
"We Orthodox Christians, following Scripture and the credal statements and the liturgical prayers, can never say there is one God who is the Trinity. There is one God who is the Father, and this one God who is the Father has with him eternally, whom he begets timelessly before all ages, his only-begotten Son, who is also his Logos, his Word, and also his Ḥokmot, his Sophia, his Wisdom, also his Eikona, his Icon, his Image. Whether we think of the one Person of the Father, who is never devoid of his Son and Spirit, whether we think of the one divinity—and here we should notice, by the way, that in Eastern Orthodoxy, the term “Triune God” is not a traditional formula. In fact, I believe you never find it in any liturgical prayer ever, the expression “Triune God.” You find the expression “Tri-Personal, tri-Hypostatic divinity,” “Theotēs” in Greek, “Bozhestvo” in Slavonic, but not “Theos” or “Bog.” There is no tri-Personal Theos, God. There is the one Theos, kai Patera, the one God and Father: “I believe in one God, the Father Almighty…” That’s the one God. But then that one God is Father eternally with his Son, who is God from God, and with his Holy Spirit. (source:https://www.ancientfaith.com/podcasts/hopko/the_holy_trinity)