Undoubtedly, the short answer is yes--Our Lord Jesus calls and uses men and women in all branches of civil service, especially the military. And our recorded history from inspired (Cornelius, David) to not (Robert E Lee) demonstrate to us that Christians served and fought in the military with a clear conscience.
But more often than not, this is not the real question one is seeking to ask. Instead, there are likely others prompting this one, questions all surrounding the conscience, such as "How could a Christian be called to take the life of another person?" or "How could a Christian take on a vocation in which the orders of a superior officer might come in conflict with conscience?" or perhaps the more modern, "How is a Christian to be a Christian in the military if proselytizing is strictly prohibited?"
I cannot speak for every Christian serving or having served in the military, but I deeply appreciated persons asking such questions. For one, it showed that persons were attempting to identify and relate; two, that in general they had a great sense of respect for the calling; and three, they were extending that respect and more to me in asking the question as I must have come to terms with these sort of questions prior to serving. So, I always waited for the person to ask the follow-up question next prior to answering.
So, how does a Christian serve/fight in the military without jettisoning their conscience, without suppressing what and Whom he/she knows to be true? Is it even possible to conceive?
The short answer? With great difficulty and much prayer. The longer answer, though, warrants a longer response than one article. So, we will take the next several articles to answer these questions. Look for the additional articles to come, and in the meantime, pray for our Christian men and women in the military--they need your prayers!