Kant did think he had a moral route back to rational faith in God, for those who need it, and he thought that at some level, we all do need something like it.

It is actually a nice question how far Descartes himself endorses the monological and metaphysically dualistic theory of mind associated with his name and his legacy in early modern philosophy. But Fichte does reject this tradition, by suggesting that an immaterial thinking substance is an incoherent notion, and a rational being whose rationality was not developed through communication with others is a transcendental impossibility.

Kant certainly was sympathetic with the metaphysical tradition of rational theology that he criticized.

When people think that moral problems can be solved by some simple strategy of calculation, that sets them up for ghastly overreaching. They think they can turn everything into a "science" the way mechanics was turned into a science in the seventeeth century. They want to turn everything over to technocrats and social engineers. They become shortsighted or simplistic about their ends, and they disastrously overestimate their ability to acquire the information they need to make the needed calculations.

Kant has been famous for his rejection of eudaimonism, but I think Kantian ethics has a great deal in common with Aristotle, and some things in common with Stoicism as well. The traditions tend, I believe, to talk past each other when it comes to happiness or eudaimonia.

Fichte is a necessary step to both Hegel and Marx.

Adam Smith saw the greed of modern capitalism for what it was - a form of destructive ambition that may have favorable effects on the productive capacities of society, but which is of no direct benefit to anyone - not even to the greedy themselves, whose illusory chase after a will-o-the-wisp leaves them morally bankrupt and unhappy.