Having served three years in the U.S. Army during a war, I may not be completely objective. In spite of the war (World War II) and a generally godless environment, I often experienced the Lord's presence. But I was a staff sergeant in the Air Corps, not a rifleman in the infantry. I carried, fired, and cleaned a rifle but never used it to kill a man. Combat troops were sorely tested. For them, war was exceedingly bitter. They had to kill enemy soldiers. I don't know whether I could have done that.
For decades, Christian thinkers have debated questions related to participation in wars. They developed five perspectives, the most familiar of which are pacifism and the "just war" theory. Pacifism includes refusal to bear arms, but it doesn't stop there. A pacifist church will have no part in military service, and neither will a pacifist individual.
The "just war" theory lays out criteria by which to determine whether a war the nation faces is just. World War II was widely regarded as just. Hitler and Hirohito had to be stopped. The problem is that the issue is not always clear-cut. Both sides in the American Civil War believed that God was on their side.
Even if there is broad agreement that a specific war is just, for prospective troops the critical issue remains: "Am I willing to kill enemy soldiers?" I would guess that nothing you see on this page helps you answer that question. Sixty-six years after I first faced it, I am ambivalent about killing as a soldier. I can snap off an answer with one side of my brain but the other side immediately replies with a rebuttal. If you were my son or grandson, I'd raise questions—as many as we can think of—and talk about them all night. I would also recommend spending much time in prayer and conversation with wise people.