26 Blasphemy is incompatible with wisdom; where the fear of God, which is the beginning of wisdom, is absent, no glimmer of intelligence survives. An instance of this is seen in the heretics' citation of the prophet's words, And they shall bless You, the true God, as evidence against the Godhead of the Son. First, we see here the folly, which clogs unbelief in the misunderstanding or (if it were understood) in the suppression of the earlier part of the prophecy: and again we see it in their fraudulent interpolation of that one little word, not to be found in the book itself. This proceeding is as stupid as it is dishonest, since no one would trust them so far as to accept their reading without referring for corroboration to the prophetic text. For that text does not stand thus: They shall bless You, the true God, but thus: They shall bless the true God. There is no slight difference between You, the true God and The true God. If You be retained, the pronoun of the second person implies that Another is being addressed; if You be omitted, True God, the object of the sentence, is the Speaker.
Source: On the Trinity (New Advent)