Is the I.R.A. Protestant or Catholic?

The IRA has had both catholic and protestant members. Ireland has a catholic majority of around 75% so most in the IRA were catholics, but they did have many protestant members.
Names like George Plant, Jack White from Broughshane in County Antrim, George Gilmore from Portadown and Erskine Childers are well known protestant IRA members. The IRA in belfast had protestant commanders such as Billy Smith, Rex Thompson and John Graham. They were nicknamed 'The Prod Squad'. Ivor Bell was another protestant IRA member who was on the Provisional IRA Army Council. The I.N.L.A was founded by a protestant Ronnie Bunting and Noel Lyttle was also a protestant member of the I.N.L.A
Irish republicanism was founded by a Protestant Wolfe Tone who once said;
"To subvert the tyranny of our execrable government, to break the connection with England, the never-failing source of all our political evils and to assert the independence of my country- these were my objectives. To unite the whole people of Ireland, to abolish the memory of all past dissensions, and to substitute the common name of Irishman in place of the denominations of Protestant, Catholic and Dissenter - these were my means."-
Any religion can be a member of the IRA
However, to give an indication of the likely statistics, the Sutton index of deaths records that, of the 394 Republican dead from the recent troubles, 366 were Catholic, 3 were Protestant and 25 were 'not from Northern Ireland' (Mostly from the Republic of Ireland and probably mostly Catholic)