More Christians ought to read Calvin's Institutes of the Christian Religion. Many people assume Calvin's writings will be dry, abstract, and difficult to understand. What you'll discover when you dive in to the Institutes is that Calvin is very accessible and edifying. I think that Calvin's ability to teach biblical truth in a clear and engaging manner is due, in part, to his understanding of the theologian's task.
The theologian's task is not to divert the ears with chatter, but to strengthen consciences by teaching things true, sure, and profitable (1.14.4).
If you'd like to get a feel for Calvin's writings you can read the Institutes online at CCEL.