MORTAL SIN keeps your soul farther from god
While the church teaches that all human life is sacred, it is not a mortal sin in times of a just war.
Mortal sin
Mortal sin
Catholics view sin as an act that God finds offensive. Catholics believe there are two types of sin, venial and mortal. Whereas a mortal sin takes a person out of God's graces, a venial sin does not. Catholics believe that all sins can be forgiven by God; no sin is too big for God to forgive.
It needs to be of:Grave matter. For example, killing someone.Full knowledge. You need to know fully that what you are doing is a sin and you need to know that it is grave. (eg. A person who has never heard that killing is wrong would not commit a mortal sin)Full consent. You need to do it deliberately with complete consent (If you had been drugged and you killed someone while still being in the state of being drugged, it would not have been a mortal sin)You need to have all three criteria to commit a mortal sin, if but one criteria is not fulfilled, it is not a mortal sin.
Using God's name in vain is surely a sin, but all sins are the same. There is really no "mortal sin". The Bible tells us that all sin is equal. Sin is sin. Yes, using God's Name in vain is usually a mortal sin as it conscious defamation or disrespect of God's Person. Sometimes it may be a venial sin, especially if one has a habit, or if one makes an exclamation out of extreme fear or distress and thus without full consent of the will or understanding of the intellect. Intent defines the seriousness of the offense.
.Catholic AnswerMortal sin: both are terrible offenses against God. a Venial sin wounds your relationship with God. It can be forgiven through a sincere act of contrition, a good and sincere act at Mass in the penitential rite, or just a sincere prayer to God asking for forgiveness for all your faults. A Mortal sin complete kills the life of God in your soul, that is why is it called mortal. One mortal sin is more than sufficient to cast you into hell for the rest of eternity and anyone dying in a state with even one mortal sin on their soul loses all hope. The *only* sacraments which can be received in a state of mortal sin are 1) BAPTISM (if you have not already been baptized), and 2) CONFESSION: the sacrament that Our Blessed Lord provided to forgive sin. To attempt to receive Holy Communion in a state of mortal sin is yet another sin, and even more serious, it is called sacrilege.
God treats all killing like a sin, even if you didn't mean it. God still loves those you are killing, no matter what or who they are.
In Catholicism, a sin may be categorized as either mortal or venial. A mortal sin is one that is grave in nature and committed knowingly and deliberately and thus in defiance of God's will. A venial sin lacks the gravity of a mortal sin, results from ignorance of God's law, or is not performed volitionally. Either type of sin may be subcategorized as an act or omission. Further, the disobedience of Adam and Eve in the garden is classified as original sin and the guilt thereof is inherited by all of humanity. Original sin, therefore, precedes the above categorizations and can be distinguished from them.
Mortal Sin. although a venial sin is Somewhat like mortal sin but not as bad.Jewish AnswerIt's a deliberate 'sin'. However, one can still atone by apologising to HaShem and asking His forgiveness in combination with never repeating that action.
It depends what your reasons is for killing or fighting the 'enemy'. Are you fighting the enemy for a reason that can be supported by your believe in God!? For that you need to be 100% sure that the other side stands for evil. Else God will judge you for the choice and actions you did.