I simply want a definition of human. Does that require faith?
Why do you want it? What additional understanding of the issues do you think a definition of human would help you gain?
Let's put it another way. What part of my thought experiment of lining up all our ancestors and being unable to point at a dividing line between human/non-human did you not understand. Why do you think (supposing for a moment that you accept evolution) that you should be able to draw such a line? I'm not trying to sneer or talk down; I'm trying to help you understand how we see it. I hope my explanations are helping.