Unity Based on Essentials & Dividing with Maturity

We would point out that we live in an age of constant offense, but you know that already. So what now? How do we weed out a fear of disagreement in the church? How do we approach those who unnecessarily stir up division, or realize when we are doing that ourselves? What are the essentials of the faith, and how do we approach people when we think they are in sin?