Direct Answer
Irenaeus measured the difference by faith and fellowship. A different practice in keeping a feast did not justify breaking communion, because the churches were still united in the faith.
Support from the Message
- Churches in Rome and the West kept Easter on a Sunday, while churches of the East and Asia Minor kept it on the actual day of Passover. - The dispute became so bad that the West was ready to excommunicate the others. - Eusebius records Irenaeus declaring that no bishop should separate those churches from communion for such a reason. - Kyle says it worked. The churches kept their own practices, honored each other, and labored to keep one Eucharist. - Kyle concludes that breaking communion was reserved for people who left the faith or churches that went way off the deep end.
Discussion Follow-up
Which differences among Christians today would pass this test, and which would fail it? Have you ever treated a small qualm as a reason to separate?