If one takes the accounts of Jesus's actions and sayings seriously (by which I mean, ignoring all of the comic book superhero elements) then it seems that's what he intended Christianity to be -- a philosophy rather than an organized religion, albeit quite heavy on the metaphysics. But if O'Reilly is claiming that's what it is now, that's just more proof that he's as nutty as a Mars bar.
American Atheists President Dave Silverman wiped the floor with Bill O'Reilly. The exchange is well worth a view. Christianity not a religion? Well, make up your own mind.
As practiced, Christianity generally fits the concept of religion far better than the concept of philosophy. However, it can also be seen as a cultural influence and as a philosophy. I tend to view it in these latter frames myself, as somebody who is not convinced in the existence of a God type of higher power, but who sees useful secular lessons in Christ's life.
Good point, even without any supernatural elements, it's a solid philosophy. But come on, did you watch the clip?
The likelihood is that Jesus didn't intend Christianity at all. He was a Jewish preacher heavily focused on the imminent end-times.