First appeared in Christopher Priest's Anticipations. Reprinted in several major anthologies edited by Terry Carr, David G. Hartwell, Kathryn Cramer, and Peter Crowther. Collected in the author's book of the same title. Nominated for the Hugo and Locus Poll awards.
Told in a kind of journal--updated annually or so--the very slow time traveler's tale is simple if mysterious to the observers, waiting decades for answers to their questions. On December 1, 1985, the disheveled man appears near the National Physics Laboratory. Scientists are puzzled, but even though they discover he's traveling backward, they are unable to get immediately the answers to the questions. His predictions of when he reveals answers pass by. They come later than he predicted. After decades, they learn that when he disappears, he slingshots into the future.
Interestingly, the books that the time traveler reads parallels the narrative itself: Robinson Crusoe, Journals of the Plague Years, and Journey to the Center of the Earth. We have a lone traveler, isolated even in the presence of many. They wonder if he carries a plague and he does infect the people--indirectly--as many work harder on peace, science, etc., knowing that future has some certainties. Finally, he reaches into the heart of what it means to be an Earthling--intentionally or no.
When they try to read the traveler's lips they find he's traveling backwards, but because they don't understand, they assume he is insane. He clearly knows more than they--about time, for instance. Towards the end, though, he shows his true face--that he sees himself as a messiah that is infecting them. They will choose him voluntarily or become robots.
There are frequent references to Jesus, so presumably the time traveler is be seen as a Christ figure (albeit, an insane one): A man comes, changes the way people think, is reviled by some, sacrifices himself for the greater good of humanity, and will come again.