This is my theory, it might be different to others: Martyrs are
people who believe in Christ and they preach to other people about
Him, trying to get more believers. But sometimes, that country
might kill him/her, because they don't want Christianity in their
country, and that death of the martyrs doesn't actually break down
the cycle, but makes it even better. So the death of the martyrs
changes the Holy Spirit in us so that we gain courage and
Christianity gets stronger and stronger.
-----------------------------------------------------------------------------------------------------------------------------------------------
Martyrs by their deaths and blood justified their love to God.
During horrible tortures they didn' t recede their belief. Thanks
to the blood of the martyrs, the Church is still alive.