Why do some evolutionist suggest that Christians made up the word Darwinism?

When according to Oxford Engish dictionary the term was used by no less than Thomas Henry Huxley (Darwin's Bulldog) as far back as 1864. It was also used by Harvard Botonist Asa Gray in Darwiniana: Essays and reviews pertaining to Darwinism and in 1889 by Alfred Russell Wallace in Darwinism: an exposition of the theory of natural selection. It was also used extensively in the writings of Stephen Jay Gould and Ernst Mayr. Perhaps someone can clarify this for me?