Today I’m talking about Baruch (sometimes Benedict) Spinoza, not the glasses-in-under-an-hour chain.

Who was he?
Spinoza was a 17th century Jewish person raised in the Portuguese Jewish community living in Amsterdam (having been expelled from the Iberian peninsula). At the age of 23 he was expelled from the Jewish community through cherim (similar to excommunication) and lived out his days as a lens and optic maker, turning down offers to work as a scholar or other honors. The majority of his writings were not known until after his death. At which time they were swiftly put on the Roman Catholic Church’s banned books list. It’s unclear whether he was a pantheist (God and nature are just two terms for the same thing) or a classical panentheist (all of nature is an expression of God, but God is more than nature), but this is the primary (though not only) reason for his cherem and having his books blacklisted.
Why was he important?
Spinoza was an incredibly important predecessor to 18th century Enlightenment, particularly in Germany. He also inaugurated, in a way, modern biblical criticism (and challenges conservatives must answer) by questioning the legitimacy of books in the Hebrew TaNaKh (Old Testament). In particular he questioned whether Moses wrote the first five books of the Bible. Further he presented the first major modern challenge to Cartesian dualism, while nevertheless retaining an idea of God as fundamentally impersonal. Also he denied, to an extent, the notion of libertarian free will (also known as the only valuable notion of free will). He is important because he set the tone for so much that followed him in biblical studies, theology, and philosophy. Eventually he would be challenged by theologians in the form of Schleiermacher, hardly a “conservative,” and then later other challenges would be offered against him up until present day.
Interesting Fact
His work crafting lenses likely contributed to his (relatively) early death as the glass dust may have scarred his lungs. Hegel said of him, during his time, “You are either a Spinozist or not a philosopher” (but I don’t like Hegel).
Where might I have heard of him
He has been mentioned or alluded to in a variety of settings and famously influenced Einstein’s spirituality. Also, if you ever go to the Netherlands, there is a lot of admiration for him (he was on the 1000-Guilder note until the Euro came along, some would call that the best reason for the Euro). He is generally either loved or loathed, very little middle ground.