If you have the right family Thomas was bapt 18 Aug.1861 Jurby (mother's surname not given in any of the Jurby bapts).
Did you see the family in the 1881 census? (on FamilySearch.org):
Household:
Name Relation Marital Status Gender Age Birthplace Occupation Disability
James CORKILL Head M Male 54 Ramsey, Isle of Man, England Farmer of 159 Acres Employ 3 Men ((Local Methodist Preacher))
Magret CORKILL Wife M Female 39 Jurby, Isle of Man, England Farmers Wife
Elizabeth CORKILL Daur U Female 21 Jurby, Isle of Man, England Farmers Daur
Thomas CORKILL Son U Male 19 Jurby, Isle of Man, England Farmers Son
Daniel CORKILL Son U Male 17 Jurby, Isle of Man, England Farmers Son
Margret J. CORKILL Daur U Female 15 Jurby, Isle of Man, England Farmers Daur
Joseph CORKILL Son Male 13 Jurby, Isle of Man, England Scholar
Alfred CORKILL Son Male 11 Jurby, Isle of Man, England Scholar
Edward CORKILL Son Male 9 Jurby, Isle of Man, England Scholar
Henry CORKILL Son Male 6 Jurby, Isle of Man, England Scholar
Joseph ALL Serv Male 22 Malew, Isle of Man, England Farm Serv
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Source Information:
Dwelling Ballavarran
Census Place Jurby, Isle of Man, Isle of Man
Family History Library Film 1342345
Public Records Office Reference RG11
Piece / Folio 5598 / 106
Page Number 4
The name is often spelt with an "h", especially after leaving the IOM, and probably depends on the clerk who recorded it, rather than having been told that spelling by the person himself.
Their marriage was in Maughold (where many Ramsey people married). The parish register has:
23 Dec 1860
James Callow CORKILL, Full age, Bachelor, Mariner, Maughold, [father] James Corkill, Shoemaker, and
Margaret CALLOW, Full age, Spinster, Maughold, [father] William Callow, Tailor.
Strangely, the IGI has recorded the groom at their marriage as being "JAS. CORKILL CALLOW" so got the names the wrong way around.
There appears to have been a child of theirs bapt in Maughold, which is a worry for you because his bapt is too close to Thomas's one, unless Thomas was bapt late, and the family (or mother) moved back to Maughold just for one bapt.
James Callow son of James Corkill & Margaret Callow bapt Maughold Parish Church 23 Mar 1862.
Even if Thomas's ages were erratic it is better to post those than give none at all. Please give his ages and where and what date they appeared, e.g. U.S. censuses?
Sue