What is the biblical basis for dual-covenant theology?

[Dual-covenant theology](https://en.wikipedia.org/wiki/Dual-covenant_theology) , or two-covenant theology, holds that there are two covenants in effect—one, the Old Covenant (with the Mosaic Law) applying to Jews, and the second, the New Covenant (through Jesus), applying only to Gentiles. I've heard some dismiss this doctrine as a politically correct attempt to make Christianity "less antisemitic." **But among its proponents, what are the biblical arguments made on its behalf?** I'd like to see arguments from both Old and New Testaments, if possible. If there are arguments that rely on translating particular verses differently than what is traditional, those would be great to include as well.