Irenaeus

Thus then does the Lord plainly show that it was the true Lord and the one God who had been set forth by the law; for Him whom the law proclaimed as God, the same did Christ point out as the Father, whom also it behoves the disciples of Christ alone to serve. By means of the statements of the law, He put our adversary to utter confusion; and the law directs us to praise God the Creator (Demiurgum), and to serve Him alone. Since this is the case, we must not seek for another Father besides Him, or above Him, since there is one God who justifies the circumcision by faith, and the uncircumcision through faith.