Can someone who fights, even maybe kills or dies, for a cause he considers right, attain enlightenment?
I wonder that after reading that some Buddhists did not share the Zen samurai's vision at all.
Actually, only warriors can attain enlightenment. All Buddhas have to die on the cushion if they’re going to wake up. It takes tremendous courage, fortitude, and self sacrifice in order to make that happen. Only a warrior possesses those qualities.
But to answer you question, the one really doesn’t have anything to do with the other. It really astounds me how often people forget that the same temple that gave us Zen is the very same one that brought us the 8th century equivalent of the Apache helicopter. Shaolin monks were no slouch with the sword. Many of them fought, many of them died, and many of them killed. Many of them were also deeply awake.
I hope it’s fairly obvious what distinguishes the Shaolin monk from your average mass shooter, John Rambo wannabe, or even the samurai. To put it plainly, the true Zen warrior wholeheartedly follows the dharma. All of his decisions are made facing emptiness. Mu doesn’t tell you blow up buildings, pick off people in the street, or to be a solider of fortune. Shunyata isn’t a lord one serves or a stilted code of beliefs one takes up to defend. Seeing emptiness, the zen warrior feels compassion. His sword is drawn with compassion. If he acts with violence, it is to further that compassion even if doing so destroys him inside. The real warrior of zen serves mushin and nothing else.
Can someone who fights, even maybe kills or dies, for a cause he considers right, attain enlightenment?
From the Dhamma's perspective, the bravest most courageous warriors are those who won the battle against themselves, not some external enemies. So, yes, it'd take a 'warrior' to attain enlightenment, but without the highlighted part above. For the act of taking life, regardless of whatever noble excuse one could come up with, is still a violation of the fundamental precepts which must be fulfilled by Sotapanna, the first of the four stages of enlightenment.
“There is the case where a disciple of the noble ones abstains from taking life, abstains from taking what is not given, abstains from illicit sex, abstains from lying, abstains from distilled & fermented drinks that cause heedlessness.
...“These are the five training rules in terms of which he is restrained.
...“Sariputta, when you know of a householder clothed in white, that he is restrained in terms of the five training rules and that he obtains at will, without difficulty, without hardship, four pleasant mental abidings in the here & now, then if he wants he may state about himself: ‘Hell is ended; animal wombs are ended; the state of the hungry shades is ended; states of deprivation, destitution, the bad bourns are ended! I am a stream-winner, steadfast, never again destined for states of woe, headed for self-awakening!" ~~ AN 5.179 ~~