its about northern ireland. in general, possibly that "love" is a bigger thing than than religion and bombs and politics, and we should learn from our history.
more specifically, theres mentions of
your catholic blues, your convent shoes (both refer to the religous problems)
your stick on tattoos (as worn by terrorists)
your holy war, your northern star (obvious..)
your sermon on the mount from the boot of your car (biblical reference (mount of olives i guess) and jab at probably ian paisley)
theres also refs. to peace talks getting nowhere, bomb blast damage
im sure theres many bigger deeper meanings but far be it from me to point out any more than the obvious.