15 But perhaps it will be argued that, when the Angel of God is called God, He receives the name as a favour, through adoption, and has in consequence a nominal, not a true, Godhead. If He gave us an inadequate revelation of His Divine nature at the time when He was styled the Angel of God, judge whether He has not fully manifested His true Godhead under the name of a nature lower than the angelic. For a Man spoke to Abraham, and Abraham worshipped Him as God. Pestilent heretic!
Abraham confessed Him, you deny Him, to be God. What hope is there for you, in your blasphemy, of the blessings promised to Abraham? He is Father of the Gentiles, but not for you; you cannot go forth from your regeneration to join the household of his seed, through the blessings given to his faith. You are no son, raised up to Abraham from the stones; you are a generation of vipers, an adversary of his belief. You are not the Israel of God, the heir of Abraham, justified by faith; for you have disbelieved God, while Abraham was justified and appointed to be the Father of the Gentiles through that faith wherein he worshipped the God Whose word he trusted.
God it was Whom that blessed and faithful Patriarch worshipped then; and mark how truly He was God, to Whom, in His own words, all things are possible. Is there any, but God alone, to Whom nothing is impossible? And He, to Whom all things are possible, does He fall short of true Divinity?
Source: On the Trinity (New Advent)