But it is written95 , say they, ‘The Lord created me in the beginning of His ways for His works.’ O untaught and insensate that ye are! He is called also in the Scriptures, ‘servant96 ,’ and ‘son of a handmaid,’ and ‘lamb,’ and ‘sheep,’ and it is said that He suffered toil, and thirst, and was beaten, and has suffered pain. But there is plainly a reasonable ground and cause97 , why such representations as these are given of Him in the Scriptures; and it is because He became man and the Son of man, and took upon Him the form of a servant, which is the human flesh: for ‘the Word,’ says John, ‘was made flesh98 .’ And since He became man, no one ought to be offended at such expressions; for it is proper to man to be created, and born, and formed, to suffer toil and pain, to die and to rise again from the dead. And as, being Word and Wisdom of the Father,** He has all the attributes of the Father, His eternity, and His unchangeableness, and the being like Him in all respects and in all things**99 , and is neither before nor after, but co-existent with the Father, and is the very form100 of the Godhead, and is the Creator, and is not created: (for since He is in essence like101 the Father, He cannot be a creature, but must be the Creator, as Himself hath said, ‘My Father worketh hitherto, and I work102 :’) so being made man, and bearing our flesh, He is necessarily said to be created and made, and that is proper to all flesh; however, these men, like Jewish vintners, who mix their wine with water103 , debase the Word, and subject His Godhead to their notions of created things. Wherefore the Fathers were with reason and justice indignant, and anathematized this most impious heresy; which these persons are now cautious of and keep back, as being easy to be disproved and unsound in every part of it. These that I have set down are but a few of the arguments which go to condemn their doctrines; but if any one desires to enter more at large into the proof against them, he will find that this heresy is not far removed from heathenism, and that it is the lowest and the very dregs of all the other heresies. These last are in error either concerning the body or the incarnation of the Lord, falsifying the truth, some in one way and some in another, or else they deny that the Lord has sojourned here at all, as the Jews erroneously suppose. But this one alone more madly than the rest has dared to assail the very Godhead, and to assert that the Word is not at all, and that the Father was not always a father; so that one might reasonably say that that Psalm was written against them; ‘The fool hath said in his heart, there is no God104 . Corrupt are they, and become abominable in their doings.’ (Athanasius 12100)
- “We confess One God, alone unmade, alone eternal, alone unoriginate, alone true, alone possessing immortality, alone good, alone mighty, Creator, Ordainer and Disposer of all things, unchangeable and unalterable, righteous and good, of the Law and the Prophets and the New Testament. We believe that this God gave birth to the Only-begotten Son before all worlds, through Whom He made the world and all things; that He gave birth to Him not in semblance, but in truth, following His own Will, so that He is unchangeable and unalterable, God’s perfect creature but not as one of His other creatures, His handiwork, but not as His Other works; not, as Valentinus maintained, that the Son is a development of the Father; nor, as Manichaeus has declared of the Son, a consubstantial part of the Father; nor, as Sabellius, who makes two out of one, Son and Father at once; nor, as Hieracas, a light from a light, or a lamp with two flames; nor as if He was previously in being and afterwards born or created afresh to be a Son, a notion often condemned by thyself, blessed Pope32 , publicly in the Church and in the assembly of the brethren. But, as we have affirmed, we believe that He was created by the will of God before times and worlds, and has His life and existence from the Father, Who gave Him to share His own glorious perfections. For, when the Father gave to Him the inheritance of all things, He did not thereby deprive Himself of attributes which are His without origination, He being the source of all things. (Hilary - Damascus 43)
Just browsing around I have found a few quotes from these folks whom all seem to think God is unchangeable.