Defining ομοουσιον
At his juncture a historical question of a doctrinal
nature arises. While the Council Fathers clearly professed that the Son is
truly God possessing the same nature as the father, did they satisfactorily
address the issue of how the Son can be truly God and yet God remain one?
Arius, remember, claimed that to hold that the Son of God and heir God is one
is metaphysically impossible.
At the time ομοουσιον could have been understood in
two ways. The first conceived ομοουσιον specifying that two or more beings share the
same common substance in a generic manner. In this sense, as two copper coins
are ομοουσιον with one
another in that they share the same substance of copper, so the Son is ομοουσιον with the Father in that he
shares the same common divine substance. This understanding would vindicate
Arius’ logic for then the Father and the Son would be two distinct realities
and so there would be two gods. Some of the Council Fathers may have understood
ομοουσιον in this
manner—content to affirm simply that the Son is truly God.
The second understanding designate that for
the Son to be ομοουσιον with the
Father meant that they are one and the same reality, one and the same being. While
it is impossible to determine whether most of the Fathers understood it in this
sense, it would appear to be the case since the charge later laid against the
Council was not that it professed two gods, but that it had fallen into modalism.
Stating that the Son is ομοουσιον with the Father could mean no that they were
one and the same divine reality, one and the same Go, but that they were one and
the same ‘person’ expressed under two different modes—as Father and as Son.
This allegation was based on a false presupposition.
Those responsible for this allegation continued to hold, as exemplified within
the Origenist tradition, that the Father embodied the whole of the Godhead—he is
God in the strict sense. To say, then, that the Son is ομοουσιον with him could easily be
construed to mean that he and the Father are one and the same ‘person’. The one
God is Father/Son. Neither now possesses his own distinct ontological identity.
Athanasius, as the authoritative interpreter
of Nicaea, grasped the radical nature of Nicaea’s ομοουσιον for he appreciated that the
Council’s declaration demanded a re-conception of God as a trinity of persons.
For Athanasius, in keeping with Nicaea, the Father alone does not constitute
the one Godhead and from whom the Son comes forth in the begetting. Rather, the
one God is the Father begetting the Son. (Obviously, the Holy Spirit must be
included within the oneness of God, but that is another story.) The Godhead is now
newly conceived. The Father’s begetting of the Son is constitutive of the very
nature of God’s oneness, and contrary to Arius’ deduction, it is metaphysically
possible to conceive of the Son as God and God as one simultaneously.
For the above reasons, the term ομοουσιον and the concept it designates is
of the utmost theological and doctrinal significance. It is, historically and
doctrinally, the most important word and notion within Trinitarian and
Christological dogma. It not only definitively defines the being of the Son as
God, but it also definitively defines that this same Son is the one who is man,
for the question addressed is whether or not the man Jesus is the divine Son equal to the Father. Thus, the Council
of Nicaea definitely defined the first incarnational truth: it is truly the Son of God, identical in
divinity with the Father, who is man. (Thomas G. Weinandy, “The Doctrinal Significance
of the Councils of Nicaea, Ephesus, and Chalcedon,” in Francesca Aran Murphy,
ed. The Oxford Handbook of Christology [Oxford:
Oxford University Press, 2015, 2018], 549-67, here, pp. 554-55)