I don't like the term "passive resistance" and what it implies. Perhaps a better expression would be "non-violent resistance". Non-violent resistance is anything but passive.
It is not about avoiding confrontation, or running away, or accommodating your enemies.
It is sincere, committed and intensely focused. It is unwavering in its stance.
Mahatma Gandhi himself said that he would rather you kill an enemy in defence of the innocent than run away and abandon those you were responsible for protecting:
At every meeting I repeated the warning that unless they felt that in non-violence they had come into possession of a force infinitely superior to the one they had and in the use of which they were adept, they should have nothing to do with non-violence and resume the arms they possessed before. It must never be said of the Khudai Khidmatgars that once so brave, they had become or been made cowards under Badshah Khan's influence. Their bravery consisted not in being good marksmen but in defying death and being ever ready to bare their breasts to the bullets.
Non-violent resistance is not for sissies, weaklings or cowards. It is for warriors -- those who are truly strong. To be a pacifist, you must be willing to confront death head-on, and be willing to die if necessary.