Christian tends to be a Northern European first name (eg used in IoM, Denmark, Sweden etc - the 'off' suffix is not a manx ending - even a name beginning with a D is relatively unusual as most Manx names derive from Mac prefixed names thus the C K or Q start. (see http://www.ee.surrey.ac.uk/Contrib/manx/famhist/fnames/index.htm)
I honestly think you are entering on a dead end and would be better looking at Scandinavia or even Dutch.