Kant's moral theism and moral despair argument against atheism

In the Critique of Pure Reason, Kant rejects the traditional metaphysical - i.e., the ontological, cosmological and physico-theological (or teleological) - proofs for God's existence. 1 In the Groundwork of the Metaphysics of Morals, Kant argues that our duties are not grounded in the divine will, but solely in the moral law (GMS IV:431). 2 Otherwise, morality would be based on religion, which would amount to theological morality and heteronomy. Hence, faith in God seems not to be necessary for a virtuous life and atheism seems to be compatible with morality within Kant's philosophy. Yet in many of his other works, including the Critique of Practical Reason, Critique of Judgment, Religion within the Boundaries of Mere Reason and his lesser known Lectures on the Philosophical Doctrine of Religion, Kant argues that 'morality leads inevitably to religion' (KPV V:125; RGV VI:6) and insists that faith in God is necessary for the intelligibility of the possibility of the highest good as the final end of the moral law. Furthermore, Kant condemns atheism on moral grounds arguing that - by rejecting the idea of God as a sufficient cause for the highest good - it rules out additional religious incentives for morality (KRV A 812/B 841), 3 leads to moral despair, weakens respect for the moral law, damages the moral disposition (KU V:540), and has a pernicious influence on society by causing social disorder (WDO VIII:146) and by robbing citizens of incentives for morality viewed as commanded and enforced by God (V-MS/Vigilantius XXVII:531). 4 This paper seeks to explore (1) Kant's moral criticism in the Critique of Judgment that atheism leads to moral despair by lacking the cognitively determinate and psychological reassuring view offered by rational faith for rendering the possibility of the highest good, i.e., the harmonious and proportionate union of virtue and happiness, intelligible, and (2) the rational, non-theistic alternatives that atheists may have recourse to which uphold the possibility of the highest good. Before tackling these issues, I offer a brief analysis of Kant's defence of moral theism and his conception of atheism