Before deportation, Moshe was well liked and no one objected to his presence. He was kind, gentle, and had dancing eyes. He was a teacher to Elie.
After the deportation and Moshe miraculously escapes, he is no longer someone the Jews want around. They want to remain positive that the stories they hear could not happen to them...in a way they want to remain blissfully ignorant of the truth. Moshe, much like the prophets in the Bible, have nothing but the truth to tell--even though it is not a pleasant truth. Therefore, the people choose not to listen and even to chastise him for what he says and what he represents (the dark side of humanity).
In the end, when the Germans show up and people start getting very worried that what Moshe has said is true, he simply disappears after telling them all once more, "You should have listened. Now it is too late for you, too."
When Moishe is deported and returns he is a completely different person, the experience has jaded him toward religion because of the horrible things he has seen. Religion was central to his life before and now that he has returned the only thing he finds worth living for is warning others of what is to come. Elie remarks that,
"the joy in his eyes was gone. He no longer sang, He no longer mentioned God or Kabbalah. He spoke only of what he had seen."
He tried to tell the Jews of Sighet what he has seen, but no one believes what he says and no one cares to listen. No one wants to hear the horrible things he is saying. Everyone ignores him.