I'm in the process of putting the finishing touches on a 1000-word popular piece for a Christian periodical, and it has been a great learning experience. My job requires a lot of writing, and I like to think that I'm pretty good at it. However, there's nothing like having a professional editor go over your work to disabuse you of any preconceived notions to that end. The editor has uncovered redundancies, poor logic, vagueness, and a lack of clear examples to illustrate the points I was making. The process has been painful, but the end product is so much better as a result. Those who are in Christian academic training need to be good writers, and that takes practice, honesty, and hard work. Just because we know the Bible does not mean that we are automatically qualified to write about it with excellence. Take every opportunity you can to write. Be ruthless with your own writing so you can improve regularly. And take feedback to heart so you can learn better the writer's craft from those who evaluate you.
If you have any good resources to improve writing skill, I'd love to learn about them in the comments.