The present essay seeks to reconsider the relation of the universal-rational ethos of Spinoza’s thought to the Jewish tradition and culture in which he was raised and socially situated. In particular, I seek to engage with two previous portrayals—specifically, those of Isaac Deutscher and Yirmiyahu Yovel—that present Spinoza’s universalism as arising from his break from or transcendence of Judaism, where the latter is cast primarily (along with Christianity) as a historical-particular and thus non-universal tradition. In seeking a potential source of Spinoza’s orientation, Yovel points to Maranno culture, as a sub-group that was already alienated from both mainstream Judaism and mainstream Christianity. By contrast, I argue that there are key elements of pre-Spinozan Jewish-rabbinic conceptuality and material culture that already enact a profoundly universalist ethos, specifically in contrast to more parochialist or particularist ethical dynamics prevalent in the culture of Christendom at the time. We will see, furthermore, that the Marrano dynamics that Yovel fruitfully highlights, in fact, have much in common with dynamics that were already in place in non-Marrano Jewish tradition and culture. As such, we will see that Spinoza’s thought can be understood not only as manifesting a Maranno-like dynamic in the context of rational-philosophical discourse, but also as preserving a not dissimilar Jewish-rabbinic dynamic at the same time. This, in turn, will point to new possibilities for tracing this latter dynamic through the subsequent history of modern philosophy and modern Jewish thought.