njsresearch:
Welcome to ireland Reaching Out!
I searched for a baptismal record for James on Roots Ireland but did not find a record with a father Matthew. I noticed you posted in Kilcumreragh civil parish. If the Carrolls were from Kilcumreragh parish then the RC parish was Tubber and records for that parish do not begin until 1821.
The 1853 Griffiths Valuation head of household listing for Kilcumreragh parish does show a number of Carrolls including a Matthew in Kilcumreragh townland. http://www.failteromhat.com/griffiths/westmeath/kilcumreragh.htm
Roger McDonnell