But wouldn't history or memory fall into some form of empirical knowledge, because at one time it was empirically experienced?
But Christianity is not like that. It's a religion based on history, meaning that it's based on a particular set of events that happened at a particular time and place, and ultimately based on a particular historical person of Jesus of Nazareth. And people empirically experienced and witnessed something, and it was written down, and then it became, well, history! So I think if we are going to count historical knowledge as a form of empirical knowledge, then by that criteria, Christianity would be categorized as empirical knowledge. Whether it really happened or not... well, that's a separate question that needs to be researched.
Interestingly, this actually separates Christianity from most other religions, in that Christianity is falsifiable, that is, its truth claims are grounded upon historical evidence that can be examined and verified or falsified.
So if you are interested in finding out more about historical evidence for Christianity, I can refer you to ask some other questions.