34 But perhaps by saying, You the only, Christ severs Himself from communion and unity with God. Yes, but after the words, You the only true God, does He not immediately continue, and Him Whom You sent, even Jesus Christ? I appeal to the sense of the reader: what must we believe Christ to be, when we are commanded to believe in Him also, as well as the Father the only true God? Or, perhaps, if the Father is the only true God, there is no room for Christ to be God. It might be so, if, because there is one God the Father, Christ were not the one Lord. The fact that God the Father is one, leaves Christ none the less the one Lord: and similarly the Father's one true Godhead makes Christ none the less true God: for we can only obtain eternal life if we believe in Christ, as well as in the only true God
Source: On the Trinity (New Advent)