Still reeling from reading Kant

I am still somewhat agape at the sheer scope of what Kant attempts in his Groundwork and the impressive rationality of it all. One thought that came to me was this: in debating against atheists, I have noticed Christian apologists still resort to the argument from morality. It is something like this (actually it isn't an argument so much as a challenge or observation): atheists have no grounds for a particular morality; yet human beings have a strong moral instinct. So: if you are an atheist, you can say something is morally wrong, but not consistently.

But Kant was attempting to find exactly these grounds. In other words, he claimed to have found a way in which moral truth was discoverable by reason alone, with or without divine help. By means if the categorical imperative, Kant was (he thought) able to put morality on a consistent footing that enables a moral discussion to ensue on the basis of rationality. The immoral would also be the irrational, on this basis.

Now, there are problems here of course, but I am just painfully aware that Christian apologists don't seem to address this claim to have found a universal basis for morality aside from divine revelation. Mind you, their opponents don't seem to be very good at putting the argument back to Christians either...

The other thing from Kant was this. Kant tries to sheer all manner of self-interest away from moral consideration. Intentions must be as pure as possible to bring about a truly moral act. As he says:

From love of humankind I am willing to admit that even most of our actuons are in confimrity with duty; but if we look more closely at the intentions and aspiratons in them we everywhere come upon the dear self, which is always turning up; and it is on this their purpose is based, not on the strict command of duty, which would often require self-denial.

My problem with his instance on the lack of self-interest in creation is that this actually dehumanises the moral agent. Why should self-interest always be corrupting in this way, so long as it is not the wrong kind of self-interest? This is what Augustine might say: one ought to love oneself IN GOD, just as one ought to love one's neighbour in God. The right kind of benefits accruing need not entirely sour a moral act. It is impossible to love, in a way, without some form of self-interest. Without self-interest of a kind, love itself disappears... it becomes merely formal, or dutiful, and not loving.