Opponents and Errors
The Reformed tradition has always had its opponents, whether those who are sometimes in error (e.g., the Lutherans) or those who are fully heretical (e.g., the Socinians). But our tradition has also had its own intra-Reformed controversies due to the fact that otherwise impeccable Reformed theologians have held views that, for example, sometimes have more in common with Lutheran or antinomian theology.
Mark Jones, "Foreword," in "By Faith, Not by Sight: Paul and the Order of Salvation, Second Edition", Richard Gaffin (Phillipsburg, NJ: PR Publishing, 2013), vii-viii.