The Maughold parish register has her marriage:
William Hardy & Margaret Christian married 24 June 1809. William from German.
No other information.

If Margaret came from Ramsey her baptism could be there or in Maughold or Lezayre (Ramsey is partly in Maughold, partly in Lezayre). Between 1773 and 1793 there are numerous Margaret Christian baptisms in those parishes [see IGI]. There are 1784 and 1786 Margaret bapts in Ramsey, and a 1787 bapt in Maughold (no other info. given).

Did you find her in the 1841 census, and do you have children's names, etc? You could look for possible Margarets based on her age in censuses and the various Christian parents' names.
Having identified possible parents, if you look at numerous Christian wills and decrees this is probably your best chance of identifying for certain which Margaret.

Sue