This is one of those funny things about the bible. The Hebrew translation of "thou salt not kill" means "thou salt not murder"
They actually condoned killing in times of war, defence, and revenge( an eye for an eye).
And by the commands of God, partook in raids known as "bans" were they would invade a "sinful" town kill every last man, woman, and child (animals included) and burn the city to the ground.
They fought in many wars against the Canaanites and Palestinians in the name of God.
now to answer your questions...
1. Is it right to kill in war?-------> yes
2. Is it right to kill someone seriously threatening your own life?-------> yes
3. Is it right to "mercy kill" someone who wants to die?--------> no
4. is it right to "mercy kill" someone who is alive but braindead, and cannot state whether they want to live or not? -----------> um.... rain check? LOL
now to finish. this way of thinking, "bans" and war and what not is one of the major differences in Jewish and Christian thinking. Turning the other cheek is a Christian (also Buddhist) concept. Although Jews condoned war and even God at the time, things changed, and as a new world order
ish thing was taken place Jesus told us to turn the other cheek obliterated the eye for an eye way of thinking.
"38"You have heard that it was said, 'Eye for eye, and tooth for tooth.'[
g] 39But I tell you, Do not resist an evil person. If someone strikes you on the right cheek, turn to him the other also. 40And if someone wants to sue you and take your tunic, let him have your cloak as well. 41If someone forces you to go one mile, go with him two miles. 42Give to the one who asks you, and do not turn away from the one who wants to borrow from you." - from the Gospels of Matthew chapter 5.
which says war and what not are wrong, fighting is wrong and advocates forgiveness and love even to your worst enemy.
"43"You have heard that it was said, 'Love your neighbor[
h] and hate your enemy.' 44But I tell you: Love your enemies[
i] and pray for those who persecute you, 45that you may be sons of your Father in heaven. He causes his sun to rise on the evil and the good, and sends rain on the righteous and the unrighteous. 46If you love those who love you, what reward will you get? Are not even the tax collectors doing that? 47And if you greet only your brothers, what are you doing more than others? Do not even pagans do that? 48Be perfect, therefore, as your heavenly Father is perfect." - from the Gospels of Matthew chapter 5.
this is just another one of those changes that occur in the bible many times due to the evolution of the earth and it's people. So as we change, as times change the way we are governed must change, not God.
my priviest answers was from a Jewish mind set, and now from a Christan's...
1. Is it right to kill in war?-------> no
2. Is it right to kill someone seriously threatening your own life?-------> no
3. Is it right to "mercy kill" someone who wants to die?--------> no
4. is it right to "mercy kill" someone who is alive but braindead, and cannot state whether they want to live or not? -----------> um....
rain check once again.