Evangelism is carrying a message you believe in to people who have not heard it yet, and doing the patient, repetitive, faithful work of helping them understand why it matters. I chose the word deliberately in 2010 and I am still glad I did — it was never a marketing euphemism, it was an accurate description.
In practice it is three audiences in roughly equal measure. Internal: getting your own organization to understand what the APIs are for and why the discipline around them matters. This is usually the largest gap and gets the least credit. Partner: helping the organizations you work with build successfully on what you offer. Public: the conferences, the writing, the community work.
The tool that does most of the work is storytelling. The technology never sells itself, the specification never explains its own significance, and the platform never makes its own case. A story connects something abstract and technical to something a specific human being cares about. I have watched excellent APIs fail for lack of it and ordinary APIs thrive because someone told their story well.
One piece of advice I give everyone who takes this work on: take care of yourself. Evangelism is a performance, it is emotionally expensive, and the people who do it best are the ones who last.
