During his Lisbon Inquisition trial in the years 1645-1647, the Portuguese Jew Isaac de Castro Tartas, defending his right to live as a Jew, noted the superior justice of the Jewish understanding of salvation, which accorded righteous non-Jews – those who observed Noahide Law - a portion in the “world to come.” His oral statement, recorded by a notary, reflects Portuguese-Jewish interest (evident in the writings of Menasseh ben Israel and Moshe Rafael d’Aguilar) in the contemporary discussion of Noahide Law among certain Christian Hebraists (Peter Cunaeus, Hugo Grotius, and John Selden). This paper will examine the polemical value of the notion of Noahide Law for Jews and some Protestants in an environment in which a principle of freedom of conscience stood increasingly at odds with the dictum extra ecclesiam nulla salus.