There is a big difference between being trained to kill and trained to preach. I for one appreciate the training of both those in our armed forces and those who have chosen to spread the Gospel.
All of us were young back then and first, you make a lot of noise, firing away at where you think the fire's coming from. Later, that changes after you gain more familiarity with the racket and confusion of a firefight and you see the first of your own dead.
You begin to see the consequences of failing and you get angry that they killed some of the same guys you had breakfast with. Then you begin to find out that you had senses you didn't know you had and you learn to accurately place where the enemy is and you aim very deliberately.
That way, more of your young friends get to go home and fewer of their young men get to kill more of us.
I just think that, given this situation where a madman is shooting innocent, unarmed parishioners and the only thing that can stop him from killing more is good sight alignment and trigger squeeze - do it and don't whine about it afterwards.