One of my closest friends is into philosophy in all kinds of ways. And he's started getting me into the discipline.
I'm preparing a study looking at the history of the idea of Christian love. It's quite interesting. I don't believe there is such a subject in theology that has been as neglected as love. It is rarely studied - only assumed to be understood.
So, I'm starting with Plato, who lived over 400 years before the development of Christianity. His view dominated the Hellenistic world in which the New Testament comes out.
It's amazing how philosophy so greatly influences religion. I'm starting to read more and Plato and looking at Platonic views in Christianity - they're there and are very obvious when you look for them.
I used to think "why does Plato matter? he has nothing to do with the Bible!" I was completely wrong. Platonic philosophy dominated the Hellenistic world and it is important to understand its thinking if we are to fully grasp what the NT writers were talking about with respect to love, for example.