Whittaker Chambers affected the anti-communist movement because he was an anti-communist writer, who spied the communists and shared all their secrets. He became respected by the American people during the 1950s.
At first, he was a member of the Communist Party and Soviet spy but then, he changed his mind and became an outspoken anti-communist.
Moreover, he was the accuser of Alger Hiss in the famous series of hearings and trials.