Even though the Old and New Testaments differ with respect to some of the tools whereby the teachings are administered (and also their circumstances), yet they agree as far as the substance is concerned. And the same Theology is advanced in both Testaments: God’s single will to redeem the human race and the one basic promise that salvation must be obtained through Christ (Gen 3:15 and Acts 22:18; Acts 15:11, and 10:43, etc.).

Synopsis of a Purer Theology, Disputation 1 Paragraph 27.