Are wars ever just? (Just War)

What is Just War Theory?
A Just War is a war that is considered morally acceptable because it is fought for serious reasons and in a fair way, usually as a last resort when peace efforts have failed.
Catholic Christianity is not fully pacifist, meaning some Catholics accept that war can sometimes be justified under specific conditions.
The idea comes from St Thomas Aquinas, who developed the Just War Theory to judge when it is right to start a war (jus ad bellum) and how it should be fought (jus in bello).
Key rules for starting a Just War include having a just cause, being declared by legitimate authority, and aiming to restore peace rather than gain power or wealth.
Additional rules for fighting include using war only as a last resort, using proportional force, protecting civilians, and ensuring the overall good outweighs the harm caused.
What is pacifism?
Core Belief and Biblical Basis: Christian pacifism is the rejection of war and violence in favor of peaceful solutions, rooted directly in Jesus’ teachings to “love your enemies,” “turn the other cheek,” and his decision
to reject violence during his arrest.
Absolute vs. Relative Pacifism: Christian pacifists generally divide into two perspectives: absolute pacifists, who believe violence is wrong in every single situation, and relative pacifists, who believe force can
occasionally be used as a last resort to protect innocent people.
Dedicated Peace Churches: Specific Christian denominations—most notably the Quakers, Mennonites, and Amish—strongly champion pacifism by refusing military service and dedicating themselves to charity
and peace work.
Arguments Supporting Pacifism: Proponents argue that because humans are made in the image of God, violence must be avoided as it kills the innocent, creates suffering, and contradicts the peaceful example
set by Jesus.
Arguments Against Pacifism: Other Christians believe that war can sometimes be morally necessary to combat evil and injustice. This viewpoint relies on the Just War Theory, which permits warfare if it is fought for
the right reasons and used strictly as a last resort.