dechristianize

from The Collaborative International Dictionary of English v.0.48

Dechristianize \De*chris"tian*ize\, v. t. [imp. & p. p.
   {Dechristianized}; p. pr. & vb. n. {Dechristianizing}.]
   To turn from, or divest of, Christianity.
   [1913 Webster]