Baruch Spinoza was excommunicated by his fellow Jews, and his works were widely banned in Christian Europe during his day:
The exact reasons for the excommunication of the 23-year-old Spinoza remain murky, but the reasons he came to be vilified throughout all of Europe are not. Spinoza argued that no group or religion could rightly claim infallible knowledge of the Creator’s partiality to its beliefs and ways. After the excommunication, he spent the rest of his life — he died in 1677 at the age of 44 — studying the varieties of religious intolerance. The conclusions he drew are still of dismaying relevance.
The Jews who banished Spinoza had themselves been victims of intolerance, refugees from the Spanish-Portuguese Inquisition. The Jews on the Iberian Peninsula had been forced to convert to Christianity at the end of the 15th century. In the intervening century, they had been kept under the vigilant gaze of the Inquisitors, who suspected the “New Christians,” as they were called even after generations of Christian practice, of carrying the rejection of Christ in their very blood. It can be argued that the Iberian Inquisition was Europe’s first experiment in racialist ideology. (link)
He was a strong believer in the individual's capacity to reason, and in democratic, secular governance:
Spinoza’s faith in reason as our only hope and redemption is the core of his system, and its consequences reach out in many directions, including the political. Each of us has been endowed with reason, and it is our right, as well as our responsibility, to exercise it. Ceding this faculty to others, to the authorities of either the church or the state, is neither a rational nor an ethical option.
Which is why, for Spinoza, democracy was the most superior form of government — only democracy can preserve and augment the rights of individuals. The state, in helping each person to preserve his life and well-being, can legitimately demand sacrifices from us, but it can never relieve us of our responsibility to strive to justify our beliefs in the light of evidence.
It is for this reason that he argued that a government that impedes the development of the sciences subverts the very grounds for state legitimacy, which is to provide us physical safety so that we can realize our full potential. And this, too, is why he argued so adamantly against the influence of clerics in government. Statecraft infused with religion not only dissolves the justification for the state but is intrinsically unstable, since it must insist on its version of the truth against all others. (link)
Just some food for thought.