Arianism was a major problem for the church of the fourth century. Arius’s heretical teaching led many astray, and caused much controversy and division in the church. The effects of Arius’s teaching are enormous, having drastically altered church history down to our own time; both in respect to Arianism itself, and even more so perhaps in the reaction of the church against it.
The central tenants of Arianism are its teaching that the Son of God is a creature, and not eternal with the Father. Arius taught that the Son of God was of a created and changeable nature, and that ‘there was when he was not’. These ideas were condemned as heresy by the Council of Nicea in 325 AD, which wrote:
“But as for those who say, “There was when He was not”, and, “Before being born He was not”, and that “He came into existence out of nothing”, or who assert that the Son of God is of a different hypostasis or essence, or created, or is subject to alteration or change – these the Catholic and apostolic Church anathematizes.”
The Council of Nicea was right in rejecting these teachings as error- and by affirming the biblical doctrine of eternal generation in the Nicene Creed, the Council refuted Arius’s error. This is possible because eternal generation and Arianism are mutually exclusive; in order for one to fully embrace what eternal generation teaches, they must reject all the distinctives of Arianism.
The doctrine of the Son’s eternal generation was articulated by the Council of Nicea in these words:
“…begotten from the Father, only-begotten,
that is, from the essence of the Father,
God from God,
light from light,
true God from true God,
begotten not made,
of the same essence as the Father…”
This doctrine that the Son was begotten of the Father “before the ages” as the Nicene Creed of 381 says, is in many ways central to the doctrine of the Trinity. Its implications fully refute Arianism. Let us briefly examine each tenet of Arianism in light of eternal generation:
“There was a time when the Son was not”: This cannot be true in light of eternal generation, since it teaches that the Son was begotten of the Father *before the ages*, that is, before the very existence of time (which was created through the Son (Hebrews 1:2)). This means that the Son “was” before the ages; it is impossible then that there “was a time when he was not”.
“Before being born He was not”: This idea sounds logical, until we recall that the Son was begotten of the Father before and outside of time (hence its not just called “generation”, but “eternal generation”). The idea of an event which occurred outside of time is beyond our human comprehension; we are creatures created in time, and have no experiential concept of what “prior to time” is like (a phrase which in itself demonstrates our inability to even speak of before the creation of time without using chronological language like “prior” and “before”). But without time, there is no change, and no time “before” the Son’s generation we can conceive of in which He could have not existed; the whole Arian proposition assumes the generation (or in Arian thought, creation) of the Son to have taken place in time. When that false assumption is removed, the Arian proposition fails. The atemporal nature of generation of the Son from the Father assures us that there was never a time when the Son was not, nor a time when the Father was without the Son.
“He came into existence out of nothing”: To be brought into existence by God out of nothing is to be created; but to be begotten inherently implies that the origin of the Son is not from anything external to the Father, but from the Father Himself. The Son, then, cannot be “from nothing” if He is from the Father Himself. Rather than being created out of nothing, the Son was caused by the Father by being begotten of Him.
In the case of all begetting, the thing begotten and the one it is begotten from are necessarily of the same nature. We see this throughout creation; every creature begets after its own kind. Never does something beget something of another kind. In the very idea of generation we see that there is implicitly the teachings that the Son is from the Father in such a way that He is a distinct person from Him, and of the same nature as Him, as having both His person and nature from the person of His Father. The mode of the Father’s generation of the Son, however, is something left a mystery to us, not revealed by scripture. What we can know is that generation is different than creation, and that it involves the subject being from the one who begat it.
“subject to alteration or change”: The doctrine of eternal generation presents the inescapable logical conclusion that the Son is of the same divine nature as the Father. As was said above, that is because it is proper to the very nature and idea of generation that the one begotten is necessarily of the same nature as the begetter. Therefore, the Son cannot have been begotten of the only true God before the ages and be of any other nature than that of His Father. The divinity of the Son, then, is identical to that of the Father. It will therefore follow that just as the Father is unchangeable in the perfection of His divine nature, so the Son is unchangeable as well, as He has that same divine nature.
We see then, that all the special tenets of Arianism are destroyed by the the scriptural doctrine of the Son’s eternal generation from the Father.