Because He says, Thee the only, does He separate Himself from communion and unity with God? He doth separate Himself, but that He adds immediately, And Jesus Christ Whom Thou hast sent. For the Catholic faith confesses Christ to be true God, in that it confesses the Father to be the only true God; for natural birth did not introduce any change of nature into the Only-Begotten God.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: ix. de Trin