Suis-je Charlie?

So, how do we see this massacre at the offices of Charlie Hebdo in Paris? Disgusting, indefensible, yes - no question.  I've gone on record more times than I care to remember saying that freedom of speech, if it is to mean anything, must include the right to offend, but I've equally gone on record to say that you have to take responsibility for your own actions.  And here, it seems to me, the two themes conflict.  The magazine - as I see it - didn't just offend.  It's whole raison d'être was to offend. It set out to offend - and not just to offend Islam.  It carried some scurrilous cartoons about the Catholic Church, among others.  So that leads us to the second string - if you set out deliberately to offend, do you have to accept that those offended against may seek to strike back - and their methods may be - shall we say, a little extreme? So, I'm Charlie - or am I?