As a loyal subject to the Imperium, the Zealot / Preacher dedicates their lives to spreading the holy word of the Emperor and the Imperial truth. To show their dedication they would gladly martyr themselves in combat while delivering justice through the bullet of an autogun, the laser of a lasgun or the blunt force of a war hammer. All that matters is that the Heretic is purged.

It is better to die for the Emperor than live for yourself.