If you are looking for a non-English classic, this is one that has survived all changes of time and is as actual today as it was in the past. A masterpiece about philosophy, about Jews, Christians, Muslims, and that they are all equal, apparently it was revolutionary in 1779, well, I think it still is revolutionary today.
The way the three monotheistic religions are depicted and the problems between their followers shown is precise and still as true as ever, sadly.
A great, important part of literature. Read it, you will enjoy it.