The Collaborative International Dictionary of English v.0.48:

Christianize \Chris"tian*ize\, v. t. [imp. & p. p.
   Christianized; p. pr. & vb. n. Christianizing.] [Cf. F.
   christianiser, L. christianizare, fr. Gr. ?.]
   1. To make Christian; to convert to Christianity; as, to
      Christianize pagans.
      [1913 Webster]

   2. To imbue with or adapt to Christian principles.
      [1913 Webster]

            Christianized philosophers.           --I. Taylor.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Christianize \Chris"tian*ize\, v. i.
   To adopt the character or belief of a Christian; to become
   Christian.
   [1913 Webster]

         The pagans began to Christianize.        --Latham.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Christianize
    v 1: adapt in the name of Christianity; "some people want to
         Christianize ancient pagan sites"
    2: convert to Christianity; "missionaries have tried to
       Christianize native people all over the world" [syn:
       Christianize, Christianise]