The Provincial Letters (Les Lettres Provinciales) is a collection of 18 letters that were written by Pascal in 1656–1657. This collection is considered a classic of French Literature. It is said that Voltaire, certainly not a friend of Christianity, kept a copy by his bed as an example of what good writing looks like.
The situation that led to the writing of these letters was the condemnation of Antoine Arnauld, the leader of the Jansenist sect within Catholicism, by both the Sorbonne and a special committee set up by the Pope. It was held that five of the Jansenist beliefs advocated by Arnauld were heretical. The Jansenists followed the teachings of Augustine that God alone determined who would be saved and that God's grace offered to his elect could not be refused, but would accomplish its desired effect without any help from the individual. The two most powerful groups in the Catholic church at this time were the Jesuits and the Dominicans. The Jesuits believed that God's grace was offered to all, but each individual had the freedom to accept or reject it. This grace was called God's Sufficient Grace. The Dominican's accepted the idea of God's sufficient grace offered to all, but that it required God's Efficacious Grace, offered only to the elect, to take advantage of it. Pascal used a comedic style and sarcasm to present his arguments. His arguments were directed most strongly against the Jesuits who were the most outspoken opponents of Jansenism.
The first four letters are primarily a defence of the views of Arnuald. Letters 5–10 are directed toward the moral laxity of the Jesuits and their justification of it. The remaining letters are a direct attack against the Jesuits where Pascal abandons the comedic style of the earlier letters and writes with great passion. The first 10 letters are presented as a conversation between an ordinary resident of Paris and a friend in the provinces concerning the events involving the Sorbonne and the religious leaders that are in the news. The later letters are addressed directly to the Jesuit Fathers. Below is an excerpt from the second letter where the speaker is addressing a Dominican Father.
But, to return to the point, father; this grace given to all men is sufficient, is it not?
“Yes,” said he.
And yet it has no effect without efficacious grace?
“None whatever,” he replied.
“And all men have the sufficient,” continued I, “and all have not the efficacious?”
“Exactly,” said he.
“That is,” returned I, “all have enough of grace, and all have not.”
this grace suffices, though it does not suffice—that is, it is sufficient in name, and insufficient in effect! In good sooth, father, this is particularly subtle doctrine! Have you forgotten, since you retired to the cloister, the meaning attached, in the world you have quitted, to the word sufficient ?
The Provincial Letters were very popular with the general public, even after they were eventually banned by the Pope. This was due in part to French nationalism and the close ties of the Jesuits with the Pope who didn't reside in France.
At his death Pascal was in the process of writing a defense of Christianity that was not completed. However, many of the notes he had prepared have been recovered. We do not know the order he planned to present the material and we don't know if all of the notes would have made into the final publication. The notes have been collected together in a volume called Pensées (thoughts). The material in the Pensées has been used both by philosophers and by Christian apologists. Probably the most famous selection from the Pensées is known as Pascal's wager. Below is a sample of Pascal's argument.
Let us then examine this point, and let us say: ‘Either God is or he is not.’ But to which view shall we be inclined? Reason cannot decide this question. Infinite chaos separates us. At the far end of this infinite distance a coin is being spun which will come down heads or tails. How will you wager? Reason cannot make you choose either, reason cannot prove either wrong.
Let us weigh up the gain and the loss involved in calling heads that God exists. Let us assess the two cases: if you win you win everything, if you lose you lose nothing. Do not hesitate then; wager that he does exist.
Pascal's argument was not designed for those seriously seeking to know God, but was designed for the secular population who avoided thinking about God and other ultimate topics through diversions such as gambling. It's goal was simply to help them see that, even from a secular point of view, belief in God was not unreasonable. It was not a method for evangelism, but could be considered as pre-evangelism. Pascal wanted to get them thinking about God's existence.