This is where I first saw the name Christian used but not sourced:
http://www.damnedcomputer.com/Genealogy/ncttimeline.htm
The two books I've found don't give a birth year:
http://books.google.com/books?id=RJcfa0INt4IC&lpg=PP1&dq=Fa...
http://books.google.com/books?id=PMI6AAAAMAAJ&dq=Joseph%20North...
Jason - you might add the sources to the Early Settlers of Milford, Connecticut project. I looked for Joseph Northrup in what I consider one of the better sources which is a complete listing of the members of the early families (book by Susan Woodruff Abbott which is listed under Sources for the project).
Shall I make you a collaborator on the project? You can add profiles regardless.
http://awt.ancestry.com/cgi-bin/igm.cgi?op=GET&db=timberdoodle&... This family tree may be the source of Christian. We could email some of these guys and ask their source.
I looked in NEGHS (New England Genealogical and Historical Society) and did not find any discussion of either his birth date or first name.
I'm guessing the birth date is not sourceable (no records) and that Christian Joseph might have been his baptismal name from when he was baptized in Milford when he was an adult (I saw that he was baptized in ~ 1643).