Perhaps I shouldn’t say “favorite.” Maybe a philosopher you’ve spent a lot of time reading.
I have to say that the philosopher I spent most time reading and trying to understand is Kierkegaard. I don’t want to get into politics or religion here necessarily, but there’s no way to really understand Kierkegaard without understanding Christianity. Now, one doesn’t need to be a Christian in order to study a Christian thinker, which Kierkegaard was.
I learned about Kierkegaard for the first time in Introduction to Philosophy, where we read Fear and Trembling, and then further in an undergraduate seminar on existentialism. That seminar, taught by a Kierkegaard expert, did manage to divorce Kierkegaard from Christianity by focusing mostly on Kierkegaard’s existential ideas.
After that course, and with help from the experts at Stetson, I studied Kierkegaard on my own. He is a difficult philosopher to understand because of his various pseudonyms, editors, and the like, who are found all throughout his work.
One thing seems clear, however. Kierkegaard seems to have thought it was not possible to make an argument for the existence of God. At the time, there were many thinkers who were trying to get at some-kind-of-Truth (capital ‘T’). Kierkegaard was very much against those projects. He seems to have thought that God can only be known by faith–making a leap to faith. But leaping to faith is itself an act of faith, which Kierkegaard was well aware of. He describes this in detail in various books and essays.
Kierkegaard was also very much concerned with Christian ethics. This is something I was reading about recently, as my specialization is in ethics. Kierkegaard thought that internal devotion was as important as outward displays. In other words, “Christian acts” are not the only thing one should be doing. One should also be internally aligned with God. This is because we can act for show, or for many other reasons. Therefore, acts of love (for lack of a different term) are not sufficient for being a Christian, though they are important nonetheless. Kierkegaard heavily emphasized the individual and her relationship with God.
So acts and internal states are both necessary for being a Christian, which was one of Kierkegaard’s central problems; How to be a Christian in Christendom.
I have found much of Kierkegaard’s writing edifying. I suggest, for an edifying discourse, to read his Works of Love. And, of course, Fear and Trembling is to be read in order to grasp one way of understanding the dilemma Abraham faced when told to sacrifice Issac.