Michael Gelven, the question: "What authors should I read to better understand Kant?" Gelven told me: "Read Kant."
But of course! Kant's Critique is one of the greatest philosophy texts ever written, in its novelty, brilliance, and clarity. Books on Kant or about Kant themselves never achieve the heights the Critique reached.
So, what would be the best texts to read to understand, for example, Jesus? The correct answer is: the four Gospels of Matthew, Mark, Luke and John. Want to read a good book on biblical prophecy? Read the Bible itself and what it says about prophecy. Begin there.
New Testament scholars go to the original languages, and not translations of the Bible. If you were a Dostoevsky scholar you would need to read Crime and Punishment in the original Russian. You would not be a scholar if you could not or did not do this.
Want to learn and grow in your Christian faith? One must begin with the actual Bible. Bypass the many books that talk about faith and the Bible, and read the Bible for itself. It is the enduring text that remains after all commentaries come and go.