In order to understand the scope of Kant's Critique of Pure Reason, one must understand a basic truth about reality: Some real, observable phenomena are transcendental, meaning that to understand them is beyond the scope of human knowledge, because they're technically infinite in nature. He treats time and space this way, arguing that people refuse the temptation to become superstitious, but not because he doesn't think the question is valuable—he just believes that the question still transcends our ability to answer it.
For a clear picture of what he means, look at his famous argument to understand God as a "Watch Maker." This deistic view means that although Kant understands in principle that God's existence would make sense of our existence, that doesn't actually help at all—in fact it might make the system even more unspeakable in nature. For Kant, the only helpful view of God is one that addresses the fact that God's design is more important in our experience than God's real action. In other words, Kant's "religious views" could be expressed this way: "The universe is orderly and significant, but religion is attempting to answer unanswerable questions, instead of letting the universe be wonderful and confusing.
Interestingly, although in its time, Kant's writing was regarded as fundamentally non-religious, it turns out that in the philosophical community, Kant seems to treat the idea of God with humility and rationality. In fact, many ideas of his view of the metaphysical world seem to correspond quite nicely with an Eastern Mystic, like Zen Buddhist for example. A Buddhist would share Kant's view that issues of theology are essentially non-dual and transcendental. They too prefer to leave religious questions unanswered, finding the journey of reasoning through one's existence to be more meaningful than just "Having a right answer" in theory.
The work is not concise, per say, but it is consistent. Overall, a reader should take away from this that Kant paved the way for freethinkers like the Logical Positivists, and that theology is really just philosophy poorly executed. The issues of existence, God, and the meaning of life are inherently transcendental, meaning that they are observable in theory, but that our ideas about such subjects should be open-handed and open-minded, given the infinite scope of a term like "God," and the limitations of our real human minds.
