Ussher went on to become Chancellor of St Patrick's Cathedral, Dublin in 1605 and Prebend of Finglas.
He became Professor of Theological Controversies at Trinity College and a Bachelor of Divinity in 1607, Doctor of Divinity in 1612, and then Vice-Chancellor in 1615 and vice-provost in 1616.
Ussher certainly preferred to be a scholar when he could be.
He engaged in extensive disputations with Roman Catholic theologians, and even as a student he challenged a Jesuit relative, Henry Fitzsimon (Ussher's mother was Catholic), to dispute publicly the identification of the Pope with the Antichrist.
Ussher was a convinced Calvinist and viewed with dismay the possibility that people he regarded as anti-Christian papists might achieve any sort of power.According to his chaplain and biographer, Nicholas Bernard, the elder brother was taught to read by two blind, spinster aunts.A gifted polyglot, he entered Dublin Free School and then the newly founded (1591) Trinity College, Dublin on 9 January 1594, at the age of thirteen (not an unusual age at the time).During a four-year interregnum between Lord Deputies from 1629 on, there was an increase in efforts to impose religious conformity on Ireland.In 1633, Ussher wrote to the new Archbishop of Canterbury, William Laud, in an effort to gain support for the imposition of recusancy fines on Irish Catholics.