Athanasius of Alexandria

Vigil. Tapsens. (ibid. p. 644): The audaciousness of this most insane error I will curb by the authority of the heavenly testimonies, and demonstrate the distinct personality of the proper substance of the Son. I shall not produce things which are liable to be explained away as agreeable to the assumption of human nature; but shall offer such passages as all will allow to be decisive in proof of His divine nature. In Genesis we find God saying, “Let Us make man in Our own Image.” By this plural number showing, that there was some other person to whom He spoke. Had He been one, He would have been said to have made Him in His own Image, but there is another; and He is said to have made man in the Image of that other.

We know that He, the Only-begotten Son of God, at the Father's bidding came from the heavens for the abolishment of sin, and was born of the Virgin Mary, and conversed with the disciples, and fulfilled the Economy according to the Father's will, and was crucified, and died and descended into the parts beneath the earth, and regulated the things there, Whom the gate-keepers of hell saw [Job 38:17] and shuddered; and He rose from the dead the third day...