Penguin Classics publishes a book called Buddhist Scriptures that does a pretty good job of exploring the breadth of Buddhist thought. There's no room for it to be a good single-volume reference to all of Buddhism—it's just too diverse and has too many important works for even a substantial fraction to fit—but it's a good way to get an idea of the lay of the land. It's very diverse, and I'd say the majority of it in practice easily fits in a Western definition of religion. Pure Land even comes off as a cousin to Christianity, in its insistence that saving ourselves isn't likely and that we should devote our practice to praying (more or less) for intersession at death by a specific Buddha, who will take us to paradise (again, more or less).