Martyrdom as communicative act

Sydney's St Andrew's Cathedral.

I have been reading in MacIntyre about different, indeed rival, rationalities. In particular, he wants to show how incommensurate different rationalities are: how it is nigh impossible to understand one from the point of view of the other without translating it into terms that limit and distort it.

Now, what attracted me to martyrdom as a subject was partly the huge dissonance it revealed between two different 'rationalities' (or perhaps 'world views'): that is to say, for the secular liberal, Christian martyrdom can only be understood as a life-denying, futile and possibly violence-perpetuation act. For the Christian, we cannot really see what the secularists concern is. And, it is worth asking at this point whether martyrdom becomes the ultimate 'no' to further communication with the other point of view - 'I am ready to accept death rather than accept your terms of conversation, or to concede anything' seems to be the attitude, or it could be read as that I guess. It is a defiance of rational discussion, apparently. Is martyrdom then merely a point at which the two world-views are shown to be irreconcilable, and that's that? Is it merely a gesture of defiance against the alternate order of power?

But: martyrdom is a remarkably successful form of communication to the non-church world. We cannot forget: the martyrs of Jesus Christ overthrew a mighty empire from within! The note that Christian martyrdom strikes is dissonant to the extent that it exposes the futility of opposition to God. It testifies to the non-ultimacy of human political power - and it testifies to that power itself. Sometimes, it seems, even the rulers and the soldiers get the message. Remember the centurion 'when he saw how Jesus died' said 'surely this was the Son of God'...'The blood of the martyrs' as Tertullian said 'is the seed of the church'. Which is to say, the blood of the martyrs convinces outsiders of the need to become insiders, to say 'I'll have what he's/she's having'.

Question is: what is it about martyrdom that communicates so well? This question asks at a deeper level: what is it in martyrdom coming as it does out of a precisely Christian understanding of the world that is able to be meaningful enough in any world-view?
Is it an exhibition of remarkable courage, or endurance, or some virtue that is found nowhere else in these proportions? Or is the meaning - the story - that the martyrs and their brethren attach to their deaths?