John Calvin wrote about theology during the Protestant Reformation, a historical era during which sweeping changes pulled the once monolithic Christian religion into many splinter sects. Calvin's writing career came after the initial break -- his work underpinned the popularization of religious reform. Today, numerous religious denominations consider themselves Calvinists.
"Institutes of the Christian Religion" is a major work intended to provide guidance and commentary for readers of Biblical scripture. It was first printed in Latin in the 1530s, and later printed in English. In fact, the original title, "Institutio Christianae Religionis," is often a source of controversy, as to whether the English title is a proper translation.
A Latin first edition published in 1536 sold in 2006 for $720,000 [source: Forbes].