The Father is without origin (principium sine principio). The Father that he is not begotten ἀγέν(ν)ητος, has no principle from which he would originate (ἄναρχος, ἀναίτιος).
The Son originates from the Father through generation, through birth/begetting.
According to Scripture
a) the Son is the natural only-begotten Son of the Father in the metaphysical sense of the word (φύσει not θέσει, i.e., by adoption). But the natural son comes from the father through generation.
b) The New Testament formally teaches this when it interprets the Old Testament passages referring to the Son's birth authentically. Thus: "To which angel did he ever say (the Father): You are my son, today I have begotten you?" [Heb 1,5–Ps 2.] "There were no seas yet, and I was already conceived." [Prov 8,24.] Furthermore: "No one has ever seen God; the only-begotten Son, who is in the bosom of the Father, has made him known." [Jn 1,18; cf. 1,1.]
c) The Father is the archetype and source of all fatherhood: "I bow my knees before the Father of our Lord Jesus Christ, from whom all fatherhood has received its name in heaven and on earth." [Eph 3,14.] Similarly, the Son is the archetype and form of all sonship: "Those whom he knew beforehand, he also predestined to be conformed to the image of his Son so that he might be the firstborn among many brethren." [Rom 8,29 cf. Gal 3,26.] But sonship is characterized by coming through generation. If this were missing in the second divine person, it would be a false or distorted archetype and pattern.
This is also the universal teaching of the Church Fathers before the Council of Nicaea. According to Justin, the Logos is the God begotten by the Father. The apologies of the teaching cast some shadow on their less fortunate attempts to connect the eternal birth of the Word with the creation of the world. In this respect, the Alexandrians and Tertullian are more precise [Justin. I 61 62; Clem. Al. Adumbr. (Μ 9, 734), Origen. in Jer hom. 9, 4; Tertull. Prax 2 8 9; Marc. II 27.].
Later, especially the Greek Fathers defended the eternity of the Son's generation against the Arians (the Arians' main argument was that the begotten is later than the begetter) [Nyssen. Eunom. (M 45, 441 ff.); Basil. Eunom. II 17; cf. Thom I 42, 2.]; as well as the necessity of this generation (according to the Arians, God could not be forced to beget, so the Son is from the Father's will, i.e., created), which however, differs from blind compulsion as much as it does from the free decision of creation [Nev. Athanas. Ctra Ar. or. 3, 60 ff. cf. 1, 21–28; Nazianz. Or 29, 1.]; and finally, its substantial and spiritual nature (according to the Arians, generation involves division), which is compatible with God's absolute simplicity [Athanas. Decret. Nicean. 13; Nyssen. Eunom. IV. (M 45, 617 ff.); Cyrill. A. Thesaur. 6.].
In summary, the Father is considered to be without origin, while the Son originates from the Father through generation, name begetting/birth. This understanding is derived from Scripture and is also the universal teaching of the early Church Fathers before the Council of Nicaea.
The Greek Fathers, in particular, defended the eternity, necessity, and substantial and spiritual nature of the Son's generation against the Arians, who believed that the Son was a created being and not eternal like the Father.
Origen [Origen. Princip. praef.] says (in Rufinus' translation): "The summary of the apostolic preaching is the Father; then the Son, 'who became incarnate and became man, although he was God, and remained as man what he was: God. The Holy Spirit is the companion of the Father and the Son in honor and dignity. From here, it is no longer clear (from the apostolic preaching) whether he is begotten or unbegotten (γεννητὸς; Jerome [Hieron. Epist. 94.] says that Rufinus falsified Origen here, who, according to him, actually raised the question: γενητός, that is, whether the Spirit came into being in time). Therefore, we must determine this from Scripture to the best of our ability."
Since we can read in him more than once such a statement: "In the Holy Trinity, nothing should be called greater or lesser" (Origen. Princip. praef. 3; cf. in Jn 2; In Rom 5, 8, 7, 13.), it is understandable that Pamphilus, Gregory Thaumaturgus, and Eusebius defended Origen's Trinitarian doctrine; and Athanasius is obviously right that Origen's dogmatic teaching is correct.
It is certain that his zealous disciple, Gregory Thaumaturgus teaches precisely: "One God, the Father of the living Word... one Lord, one from the only one, God from God... one Holy Spirit, whose existence is from God; a complete Trinity, which is not divided or separated in glory, eternity, and dominion." The great weight of this testimony is that even simple believers knew and used Gregory's exposition of faith by heart, as Gregory of Nyssa testifies about his grandmother, Macrina. Cyprian, in particular, teaches the consubstantiality of the three persons clearly and decisively.
Just a few years after Arius' appearance in 318, the fathers of Nicaea solemnly declared the consubstantiality of the Son with the Father, and Athanasius could throw it in the faces of the Arians: "We have shown that this view has been handed down from generation to generation among the fathers; but you, new Jews and sons of Caiaphas, which fathers can you refer to?" (Athanas. Decret. Nicaen. 26.)
Indeed, the Arians did not feel the ground of the ancient ecclesiastical teaching under their feet, and therefore resorted to various ambiguous formulations and split into factions. On the other hand, the 4th-century fathers, as one man, took the position of the Nicene Creed, including the Cappadocians.
The creation of the world is an exclusive divine activity. God is the one principle of everything, the creator of everything. This is denied by the Gnostics and all kinds of other dualists, who place a world-creating demiurge between the absolutely supreme and holy God and the completely evil matter, who then, as a creature, carries out creative activity.
Proof. In the Old Testament, God declares: "I am the Lord, the maker of all things, who alone stretched out the heavens, who spread out the earth by myself" (Is 44:24). John says of the Word: "All things were made through him, and without him was not any thing made that was made" (Jn 1:3; cf. Heb 3:4 Ap 4:11. Act 4:11 Rom 11:36).
The Church Fathers first proclaimed the Christian truth against the Gnostic demiurge (Iren. II 1-3; IV 21, 1). However, their main argument against the Arians was: The Word (whom they call a creature) created the world, therefore it must be God; a creature cannot create (Athanas. Ctra Arian. II 21 24; Nyssen. Eunom. II (M 45, 512c); Cyril. Al. C. Iulian. II.). Augustine vigorously opposed Philo's explanation that at the beginning of Scripture (Gen 1:20-26) God would have called on the angels to be his helpers in creation (August. Gen. ad litt. IX 15, 26 - 28 Civ. Dei XII 24; Trin. III 8, 13; cf. already Iren. I 22, 1; II 2, 4; IV 20, 1).
No existing or possible created being can possess creative power, not even in a supernatural way. For the creative activity presupposes infinite power. Because a) it creates something against nothing, which is separated from nothing by an infinite distance; bridging this infinite distance demands infinite power. b) Creation is directed towards being itself, the most universal reality, without any limitation from determinations and pre-existing matter; therefore, it is essentially unlimited power: whoever can create something can create anything at will. However, finite creatures cannot accept infinite capacity as a determinant of existence or as an accessory: the extent of the receiving subject sets a limit to the content of being that can be accepted; an infinite ocean cannot be poured into a finite container.
Moreover, a creature cannot even be made an instrument of creation. Because a) the task of the instrument is to prepare the material for the acceptance of the activity of the principal cause. But creation does not aim at existing matter; therefore, there is no exercise area (materia circa quam) for its operation. Most importantly, b) the instrumental causes must receive motion from the principal cause and transmit it to the matter, which must be shaped according to the intention of the principal cause. However, a finite creature, as such, is incapable of taking up and carrying the creative activity with infinite content, just as a stone or log is incapable of being the substantial carrier of spiritual activity, even in a supernatural way. Of course, there is no obstacle to a creature being the occasional cause (causa occasionalis) of a creation-like miracle; this, however, only means moral cooperation.