Tolerance

Pierre Bayle

The modern idea of tolerance goes back to what Baruch de Spinoza and John Locke have written about it. Of course, they had their predecessors, such as Montaigne and the Dutch Renaissance scholar Dirck Volckertszoon Coornhert (1522-1590). Less known is Pierre Bayle’s contribution to the development of the idea.
Pierre Bayle (1647-1706) was a French Huguenot who had to flee from his country because of his religion. He lived many years in exile in Rotterdam in the Netherlands, where he also died. He was one of the leading scholars of the Early Enlightenment. One of his main works was Tolerance. A philosophical commentary (abbreviated title), published in 1686. In this book he developed one of the “three leading tolerance conceptions of his time”, so Buddeberg and Forst (p.21). The work must be seen against the background of the persecution of protestants in roman-catholic countries in the 17th century, especially in France. Before Bayle, Spinoza had already argued for an individual freedom of religion, although the state could order which religion would be publicly practiced within its territory. A few years after Bayle Locke argued for a separation of church and state. Religions should be allowed to organize themselves in voluntary societies and there should be freedom of conscience. The state could interfere only when a religion would question the authority of the state and when a denial of the existence of God would undermine the moral foundations of society. (ibid.) Bayle was more radical and pleaded for freedom of conscience anyway
Bayle’s Tolerance consists of two parts. In part 1 he rejects the arguments based on Augustine’s view that it is allowed to force non-believers with violence to accept the right Christian faith. In part 2 Bayle discusses possible replies to his arguments in part 1. One can summarize Bayle’s argumentation against violent non-tolerance as follows: Violent non-tolerance is either 1) hypocrite, or 2) it is senseless, or 3) it is counterproductive. Let me explain. 

1) Bayle says, for instance: Assume your faith is a minority faith in the country where you live and you are persecuted by the defenders of the main religion (as was the case in the early days of Christianity in the Roman Empire, for example). Or you are sent as a missionary to China, but the Emperor of China chases you away by force. What would you say then? Indeed, your view would be that the rulers have no right to do so and you’ll detest what they do. But what right then do you have to persecute and kill others who don’t accept your faith, when you are the ruler of a country? It’s hypocrite to think that you are allowed to persecute non-believers in case you have the power to do so. You are not allowed to do to others what you don’t want that they do to you.
2) Persecuting those who don’t have your faith is not only hypocrite, often it is also senseless. Assume now that you are persecuted for having a minority religion. For example, you are a Huguenot in France at the end of the 17th century. You are not allowed to have public and many non-public functions any longer. Your possessions are robbed by the state. Many people with your religion are tortured because of their faith and you fear to be tortured, too. You can even be killed because of your faith. What will you do? It’s not unlikely that you’ll think: Let me pretend that I have given up my faith and let me feign that I have accepted the official religion. And so you do and from then on you go to the state church or temple and you do the prescribed rituals. But in your heart you still belief what you always believed. Your conversion is mere appearance. The tries to convert you by force have been senseless.
3) It is also possible, however, that the violent tries to convert non-believers fail and just make that they are strengthened in their belief. Doesn’t the Gospel say already that your faith will be badly received by the world? That’s what you are experiencing now, and you think that your salvation is in the hereafter, not in this world. If non-believers react in such a way, tries to convert them with violence are simply counterproductive. 

These are the main reasons why Bayle pleads for a complete tolerance of all religious views and for freedom of conscience. He wants a tolerance of different and dissenting religious views, anyhow. Actually, there is only one standard for what you believe: your conscience. For what else should decide which religion, view or opinion is true? Who will say which conviction is best? It is absurd to say that there is a criterion to decide this. If you think that such a criterion exists, what actually happens is that the strongest wins and that the arguments of the strongest are seen as best. Then being true and being the strongest are different words for the same. Or, as Bayle also says: We give a beautiful name to what is ours but hold in contempt what belongs to others.
Bayle aimed against religious intolerance, but his arguments are valid against all kinds of intolerance. It makes Bayle one of the founders of the modern idea of tolerance, together with Spinoza and Locke. Although now Bayle is less known than them, his view has certainly been as influential. 

Source
Pierre Bayle, Toleranz. Ein philosophischer Kommentar. Herausgegeben von Eva Buddeberg und Rainer Forst. Frankfurt/Main: Suhrkamp, 2016.
There are several English editions of Bayle’s Tolerance. Just google.