There are practical reasons to believe in Abraham Lincoln based on "testimony" as you put it. For myself, I don't choose to come down as being an expert in Evolution, the Theory of Relativity, what happened on 9/11, or anything else I don't have personal experience with.
What I truly know and understand about this world would fit into a thimble. My experience tells me that if I touch a hot stove my hand gets burned. I don't need anyone else's testimony to help me understand that if I drink 12 beers i may puke.
Unfortunately, many people forget about experience and begin trusting others for nearly everything, including religion. It is true that i put my trust in some basic assumptions (such as Abraham Lincoln's existence) in order to function in society.
I do not believe Christianity, Judiasm, or any other religion fits at all into the category of commonly excepted truths.

g