The "Just war theory" is not biblical and will not stand before GOD. We can't expect to end our life prematurely and be forgiven by God. The Almighty is a just God but also a most terrible God. If one is in chronical pain then he/she deserves to be, else God would have decided otherwise. No man is blameless more so no woman, because she was the beginning of sin.
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What does Christianity teach about war and peace?
The Bible does not give Christians a clear answer about whether war is permitted or not, but it has a lot to say about justice, the sanctity of life, the importance of resolving conflict and working for peace.
Most Christians believe that war should be avoided if possible, and should only be undertaken if all efforts to resolve an issue by peaceful means have failed. Many Christians see war as the result of a failure to live by God's standards.
There are many promises in the Old Testament that war will come to an end in the perfect Kingdom of God.
In Isaiah it states:
They shall beat their swords into plowshares, and their spears into pruning hooks; nation shall not lift up sword against nation, neither shall they learn war any more.
Isaiah 2:4
Christians are told by St Paul in Romans to support the state:
For the same reason you also pay taxes, for the authorities are ministers of God, attending to this very thing. Pay all of them their dues, taxes to whom taxes are due.
Romans 13:6-7
Most Christians think that fighting for your country is included among these 'dues'.
However, some Christians are pacifists and believe that war is never justified.
What do Christians say about justice?
Christians believe that justice comes from God and they should work for justice in whatever situation they find themselves. They will often use Psalm 82 from Old Testament to justify this position:
Defend the rights of the poor and orphans; be fair to the needy and helpless. Rescue them from the power of evil men.
Psalm 82
How is the sanctity of life relevant to war?
Christians believe that God gave them life and that each human is made 'in the image of God'. Christians therefore believe that life is sacred and should be protected. The Ten Commandments forbid murder and in Matthew, Jesus tells his followers to:
Love your enemies and pray for those who persecute you.
Matthew 5:44
Some Christians believe that there are times when the only way to defeat injustice or defend the idea of the sanctity of life is to declare war. Other Christians think that they should only use peaceful and non-violent methods. Jesus told his disciples:
If anyone strikes you on the right cheek, turn to him the other also.
Matthew 5:39
Jesus' peers would have understood a slap on the right cheek as a very serious insult. Jesus is telling his followers not to respond in the same way.
Just before his arrest, in the Gospel of Luke, Jesus told his followers:
And let him who has no sword sell his mantle and buy one.
Luke 22:36
This suggests that Jesus accepted the right to be able to defend yourself.
Holy war
The concept of holy war, a war 'on behalf of God', developed at a time when the Christian church was becoming increasingly politically powerful. The Crusades, which were ordered by various Popes and took place between the 11th and 13th centuries, are the most famous examples of holy war. The intention was to recover Jerusalem from the Muslims. The Crusades resulted in many atrocities being carried out in the name of God.
The concept of holy war is rejected by all mainstream Christian Churches today.
And
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What is a just war?
A just war is a war which is declared for right and noble reasons and fought in a certain way. A just war is not a war that is ‘good’ as such – it is a war that Christians feel to be necessary or 'just' in the circumstances, when all other solutions have been tried and have failed. It is a necessary evil and a last resort.
Christianity is not a pacifist religion although there are pacifists in most Christian denominations. Some Christian groups, eg the Religious Society of Friends (Quakers), oppose war in all circumstances.
Most Christians would support a war if it were justified by just war standards.
What is the Just War theory?
The Just War theory was first developed by St Thomas Aquinas. Aquinas was one of the most influential theologians of the last 1,000 years. The theory set out conditions against which to judge whether or not a war should be waged (jus ad bellum) and if it could be justified, and how it should be waged (jus in bello).
Aquinas's conditions for a Just War – jus ad bellum
The war must have a just cause - eg against invasion, or for self-defence - and not to acquire wealth or power.
The war must be declared and controlled by a proper authority, eg the state or ruler.
The war must be fought to promote good or avoid evil, with the aim of restoring peace and justice after the war is over.
Later conditions developed by other Christians - jus in bello
The war must be a last resort when all peaceful solutions have been tried and failed, eg negotiation.
The war should be fought with 'proportionality', with just enough force to achieve victory and only against legitimate targets, ie civilians should be protected.
The good which is achieved by the war must be greater than the evil which led to the war.
The Just War theory, with some amendments, is still used by Christians and others today as a guide to whether or not a war can be justified.
Why do some Christians support the principle of the Just War theory?
Sometimes war may be necessary and right, even though it may not be good. In the case of a country that has been invaded by an occupying force, war may be the only way to restore justice. Pope Benedict XVI said defending oneself and others is a duty.
When wars are fought to protect people it could be seen as an example of Jesus' teaching:
Love your neighbour as you love yourself
Matthew 22:39
Righteous anger is sometimes justified, eg when Jesus was angry about the presence of money lenders in the Temple, he is said to have:
made a whip out of cords, and drove all from the temple area, both sheep and cattle; he scattered the coins of the money changers and overturned their tables
John 2:15
Righteous anger is about using one's anger in a way that is thoughtful and controlled to bring about about justice or to protect the weak.
My thoughts are you must not confuse the theory of 'Just War' with Euthanasia.
They are by far, two different things.
I do know Jesus was compassionate, kind and has perfect love towards us all. If it hurts us to watch our loved ones pass painfully, it hurts him more.