Friendship with God is essentially friendship with self-subsisting truth and so is the height of philosophy, for it is to be intimately one with the true.
As for the starving/fasting issue, clearly the difference is based on the end -for a person can starve themselves to fast in order to perform a supererogatory work?
Philosophy is compatible with faith, but it needs to be the servant of faith, not the master.
If you are a believing Catholic, there are several reasons to feed the hungry:
- Jesus told us to.
- The Church tells us to.
- St. Thomas Aquinas, a few months before his death, said, “I can write no more. All that I have written seems like straw.” Aquinas was a great genius, an extremely holy man, and he had spent most of his adult life writing. His works are of incomparable value to all Catholics, and to some extent non-Catholics as well. But he was right that philosophy is like straw compared to the love of God. And God loves all people, even atheists.

When you find your understanding of philosophy going against the teachings of the Church (let alone the direct teachings of Jesus!), your understanding of philosophy is wrong. Humility is your friend here. It’s a hard hurdle to jump, but worth it. You’ll get a better signal-to-noise ratio in responses if you make it clear that you know you are missing something in your reasoning, but are not sure what it is.
Philosophy is not capable of providing all the knowledge of God that humans can attain. For one thing, humans are not thinking machines. God is not merely the Truth, he is also the Way and the Life. It is not enough to know about God, you must also know God Himself. He is not merely wisdom, but love as well.
In any case, as someone else has pointed out, from a purely practical standpoint, dead people don’t convert.
And as someone else pointed out, if you feel all sinners should starve to death, then that means all humans over the age of reason should starve to death. There are not two classes of people, sinners and non-sinners. “All have sinned and fall short of the glory of God.”
Finally, metaphysics is not the source of morals. Metaphysics is a study of human nature, not the source of it. The source of morals is God and revelation. Metaphysics is useful for understanding the purpose of the content of morality, and understanding the purpose of human life. It does NOT determine what that content and purpose will be.
–Jen