Simply ask, why is the New Testament not included among the texts of Philosophy courses, though it addresses philosophical questions? Anyone speaking for philosophy today – let’s name this character Derrick – will likely tell you the answer is obvious:  

In philosophy you study philosophical answers to philosophical questions, not theological answers. Theological answers would be relevant only to Christians, and philosophy is for everybody.

If you wished for clarification on that point, what would it be? Derrick would reply,

Philosophy happens to be that discipline that looks at certain deep questions free of any prior commitment to an outlook.

But however obvious this answer might be, it is very odd. It will not likely be immediately apparent that these two claims cancel each other out.

People in philosophy who are ready to make the first claim do not appreciate that the philosophy they represent is not free of prior commitment. Only a person committed to a certain outlook would say the first of these two things, heading them for collision with the second.

If philosophical questions are to be answered ‘philosophically’ (whatever that means) there must be some reason to call for this restriction, and it turns out that that reason is, ‘Because this is the way a modern person thinks – without recourse to theology’.

Well, then, so much for looking at deep questions free of prior commitments.

A modern person does philosophy this way why?

It is no requirement of ‘reason’ (Thomas Aquinas reasoned with reference to God).

It has nothing to do with the ‘inherent nature of the practice of philosophy’ (Socrates, Plato, the Stoics, which everyone calls real philosophers, all considered problems with reference to a divine order).

And it is not because arguments free of theology are more universally accessible. Accessibility is a plus, but philosophy has never limited itself by such a consideration. Since when, in the eyes of philosophy, did an accessible answer push out a good one?

No, the honest answer to the opening question is that modern people don’t settle things by thinking about God because that is not who they are.

Thinking ‘philosophically’ turns out to be doing philosophy the way we do philosophy who (in ethics, epistemology, etc.) simply ignore the question of God. ‘Philosophical’ thinking is now the thinking of those who have adopted a certain position on the world (those with a set metaphysics). And this is just the position Derrick spoke out against.