Nearly four centuries ago the Puritan William Perkins drew a useful distinction. He suggested that there is a working difference between error and heresy. He wrote that error of itself is no ground for breaking fellowship, that any doctrinal discrepancy between two Christians means that one or both are in error. The Bible does not on that account command them to separate from each other. Heresy is another matter; heresy is error, but error that strikes at the very roots of the faith, and heresy is always grounds for breaking fellowship.