Martyrs

Lately I've been thinking about what martyrdom means. For many Christians, martyrdom is the ultimate way to show one's devotion to Christ. Kierkegaard says that unless we are willing to lay down our lives for Christ, we are not true Christians.
In the early parts of the Christian Church, there were many martyrs killed by the Roman Empire. These martyrs are widely looked up to for their courage and fidelity. Most became saints because of their martyrdom. The Emperors Domitian and Diocletian persecuted Christians openly and sent many to their deaths in grueling manners.
St Stephen is widely viewed as the first Christian martyr, and his death is recorded in the Book of Acts. Most of the Apostles were martyred. Peter was crucified upside-down. Paul was beheaded by Emperor Nero because he was a Roman Citizen.
With all the praise that goes to the Christian martyrs, it is also important to note that not every martyr's cause is a true cause.
Many unjust men and faulty causes have used martyrdom to prove correctness. Jim Jones thought that the fact that government was pursuing him proved that he was correct. Many suicide bombers and terrorists view their deaths as proving their point. The Heaven's Gate cult thought their suicides would bring them eternal joy on Hale's Comet. The arrest of Warren Jeffs only strengthened the FLDS Church's resolve.
In addition to this, what of the different martyrs from different faiths? There were the Christian martyrs, there were Jewish martyrs, Muslim martyrs, Buddhist martyrs, and Mormon martyrs. How do we reconcile so many martyrs with so many different faith traditions? Do we just look at the faith that has yielded the most martyrs?
I have heard that the Twentieth Century brought about the most Christian martyrs, especially with the wars that were fought and the genocides that occurred. How are the deaths of men like Dietrich Bonhoeffer to be compared with men like David Koresh?
We can look up to martyrs, but we cannot say that because somebody is a martyr, their faith is valid. Plenty of men have died for unworthy causes. Plenty have lived for worthy causes. Where we really need to look is not on the actual martyr, but on the cause that the martyr defended.