(In fact, the predecessors of the IRA--- the Fenians and the IRB --- were secret organizations whose members swore an oath, before God, to take their orders from the Brotherhood. This led to problems with the Catholic Church who went so far as to excommunicate members who took such an oath. Later on, IRA-Provo's and their supporters --- including, admittedly, the occasional sympathetic priest --- were told that they should not receive communion; they should effectively "excommunicate themselves.")
By way of contrast, the Islamic terrorists operate with the support of:
Other than that, of course, they're just the same...
The Catholic idea of "martyr" is almost the diametrical opposite of the Islamic idea. You'll notice that none of the warriors of 2000 years of Christendom --- not Charlemagne, not Charles Martel, not Baldwin, not Raymond, not Tancred, not Don John of Austria, not Philip of Spain not Jan Sobieski of Poland--- not one of them is honored by the Catholic Church as either saint or martyr.
Only two warriors I can think of, offhand, who were canonized were St. Joan of Arc and St. Louis IX of France...and the latter was not lauded for his prowess or success at war, but for his justice and charity.
Hmm. Interesting.