Tertullian

“ These are Marcion’s Antitheses, or contradictory propositions, which aim at committing the gospel to a variance with the law, in order that from the diversity of the two documents which contain them, [7] they may contend for a diversity of gods also. Since, therefore, it is this very opposition between the law and the gospel which has suggested that the God of the gospel is different from the God of the law, it is clear that, before the said separation, that god could not have been known who became known [8] from the argument of the separation itself. ”