Anyone who has any goal or motive apart from God is already set up to act against God. Pride consists in making ourselves the criterion.
Christians cannot go to war as followers of Jesus, because Jesus has no teaching about how to defend oneself against enemies except by “enduring evil with love.” He teaches explicitly that those who try to save their lives in this world will lose their souls. So when Christians go to war they have to go to war as people who follow the teachings of Jesus and something else, usually the demands of their nation and its government. This is idolatry.
NO POWER BUT LOVE
Rev. David Knight, PhD (Moral Theology, Catholic University), 60 years a Catholic priest, author of forty books on Catholic Faith and teaching. For further biographical information see, https://cdom.org/father-david-buell-maria-knight-obituary/
God is pleased with nothing but love.
One act of pure love is more precious in the eyes of God
and of the soul, and more profitable to the Church,
than all the good works together,
though it may seem as nothing.”
– St. John of the Cross