Just the facts ma’am

In all of the recent discussion regarding Christian freedom we have consistently heard, and I have consistently stated, that we must agree on the essentials, and allow for freedom on the non-essentials. This has caused me to question, what is essential? In other words, what are the primary issues that we MUST agree on in order to partner together and call each other brothers and sisters in the faith. I'm working on a project and I would really like to hear what you have to say about it. **UPDATE** To clarify, I would like you to list for me what items that you consider to be essential. This will be helpful to a project that I'm working on. Thanks!!