And yet earlier in the very same work, that author says:

"This salvation, which was first announced by the Lord, was confirmed to us by those who heard him. God also testified to it by signs, wonders and various miracles, and by gifts of the Holy Spirit distributed according to his will." (Hebrews 2:3b-4)

Here he presents three types of evidence which are meant to corroborate Jesus' words:

1. The eyewitness testimony of the original disciples

2. Testimony from God, in the form of signs, wonders, and various miracles

3. Evidence of the Holy Spirit in the early Christians.

I don't personally see that the world is round; or that microbes and viruses exist and make me sick; or any number of other things which modern science tells us. Yet I have assurance that they are true. That's the kind of faith the authors of the New Testament are recommending (including the author which you quote).

Just to make sure: are you really saying that the original Christians were kind of empiricists? And that mainstream Christianity isn't about "belief in the unseen"?

So I misunderstood the person I was replying to. I thought he was saying that supernatural was outside of evidence; but he meant more specifically empiricism; which literally means sensory data, but probably he means to extend to the sorts of repeatable physical tests.

[EDIT] Christianity is certainly about belief in the unseen. My claim was simply that it was belief in the unseen based on sufficient evidence, as opposed to belief in the unseen specifically without evidence.

I wouldn't expect a self-aware NPC from within World of Warcraft to be able to prove the existence of humans by doing repeated tests; by definition whatever tests he does will be mostly following the rules of the system that he's in. Such an NPC could ask for specific things to be done by an "alleged" human, which would provide evidence. Whether that sort of non-repeatable evidence counts as "empirical" in the philosophy of science, I don't know.