are you sure of Wm Christians birth year + parish ? - the census info varies but in 1861 claims Onchan as birth parish - also ages in all censuses + burial would indicate birth around 1797
this looks to be compatible with a possible son of John Christian of Beogoade (various spellings) + Elizth Gill baptised onchan 1797-02-19
The entry is found in the Bishop's transcripts for that year
if I am correct then should be relatively easy to trace back via land records eg one deed has dated 16 Jan 1717/8;James Christian(Onchan) + wife Ellinor als Kerran settle of son Philip Christian half our estate of Begoade rent 32s