Zélie didn't opt for today's traditional white dress (indeed, the white dress was only just beginning to become popular at the time of the Martin marriage). Although her wedding robe was not preserved, it would have been similar to the one in the image. The modern Christian bride may still want to choose something beautiful that hearkens back to the days when white wasn't the only option.
Photo courtesy of
http://www.louisandzeliemartin.org.