13 To resume the argument; this title of office indicates no difference of nature, for He, Who is the Angel of God, is God. The test of His true Godhead shall be, whether or no His words and acts were those of God. He increases Ishmael into a great people, and promises that many nations shall bear his name. Is this, I ask, within an angel's power? If not, and this is the power of God, why do you refuse true Divinity to Him Who, on your own confession, has the true power of God? Thus He possesses the true and perfect powers of the Divine nature. True God, in all the types in which He reveals Himself for the world's salvation, is not, nor ever can be, other than true God.
Source: On the Trinity (New Advent)