mover,” an “everlasting immovable being,” who is one and eternal, necessary, immutable, free from
all composition, devoid of potentiality, matter, change; and who is pure act, pure form,
unadulterated essence, absolute form, “the very nature of a thing, primary substance.”14 Philo
called God “unchangeable, self-consistent, invariable, steadfast, firm, fixed, unalterable.”15 And
with this assessment Christian theology concurred. God, according to Irenaeus, is always the
same, self-identical.16 In Augustine, God’s immutability flows directly from the fact that he is
supreme and perfect being: “It is instinctual for every rational creature to think that there is an
altogether unchangeable and incorruptible God.”17 This concept of an eternal and unchangeable
being cannot be obtained by the senses, for all creatures, also humans themselves, are changeable;
but within their souls humans see and find the immutable something that is better and greater
than all the things that are subject to change.
If God were not immutable, he would not be God.18 His name is “being,” and this name is “an
unalterable name.” All that changes ceases to be what it was. But true being belongs to him who
does not change. That which truly is remains. That which changes “was something and will be
something but is not anything because it is mutable.”19 But God who is cannot change, for every
change would diminish his being. Furthermore, God is as immutable in his knowing, willing, and
decreeing as he is in his being. “The essence of God by which he is what he is, possesses nothing
changeable, neither in eternity, nor in truthfulness, nor in will.”20 As he is, so he knows and
wills—immutably. “For even as you totally are, so do you alone totally know, for you immutably
are, and you know immutably, and you will immutably. Your essence knows and wills immutably,
and your knowledge is and wills immutably, and your will is and knows immutably.”21 Neither
creation, nor revelation, nor incarnation (affects, etc.) brought about any change in God. No new
plan ever arose in God. In God there was always one single immutable will. “[In God the former
purpose is not altered and obliterated by the subsequent and different purpose, but] by one and
the same eternal and unchangeable will he effected regarding the things he created, both that
formerly, so long as they were not, they should not be, and that subsequently, when they began to
be, they should come into existence.” In creatures the only change is from nonbeing to being, from
good to evil.22 The same idea comes back repeatedly in the scholastics and Roman Catholic
theologians23 as well as in the works of Lutheran and Reformed theologians.24
This immutability of God, however, was frequently combated from the side of both Deism and
pantheism. In the opinion of Epicurus the gods totally resemble excellent human beings, who
make changes with respect to location, activity, and thought (etc.); and according to Heraclitus
and later the Stoics, the deity as the immanent cause of the world was also caught up in its
perpetual flux.25 Opposition to God’s immutability in Christian theology was of the same nature.
On the one hand, there is the Pelagianism, Socinianism, Remonstrantism, and rationalism, which
especially opposes the immutability of God’s knowing and willing and makes the will of God
dependent on—and hence change in accordance with—the conduct of humans. Especially
Vorstius, in his work On God and His Attributes, criticized the immutability of God. He made a
