The "Kingdom of God" as a Kantian metaphor

The argument of this article is that Kant's philosophy of religion cannot be defined as merely ethical. The metaphor of the 'Kingdom of God' posits an original theme, introduced by morality, but going beyond. Both the question of a possible substantialization of morality itself (in: "Religion within the Limits of Reason Alone") and the question of its fulfillment in the highest good (in: "Critic of Practical Reason") need a religious answer. Most of all, the problem of evil confronts morality with an enigma, which morality is unable to solve ("Religion within the Limits of Reason Alone"). Such bipolarities like freedom and nature, virtue and happiness, evil and redemption, are neither viable in a metaphysics of freedom nor in one of nature alone. They infer a tension that persists through the reciprocal implication of both domains. Only a religious language seems apt to express this irreducible intertwinement. When dealing with ethical topics, Kant continues to recall the plus-point of religion, which not surprisingly he considers to be the realm of hope, the answer to his third critical question. Religion incites a humble respect for the reality of the divine Creator, Legislator, and Judge, and kindles love for the personal (Christian) God. As such, this could never be the result of ethics, nor of a metaphysics of nature. Accordingly, the coherence of nature and freedom is the existential question that points to the original metaphorical language of the 'Kingdom of God'.