An API is useless if nobody knows about it. Evangelism has emerged as the approach to selling, marketing and support an API platform. While the intent of evangelism can be sales and marketing, the philosphy that has proved successful is to find a balance that is more about focusing on API support and egagement with consumers over sales.
A healthy API evangelism strategy brings together a mix of business, marketing, sales and technology disciplines into a new approach to doing business.
A healthy API evangelism strategy will be something that is owned partially by all departments in a company. IT was a silo, APIs are about interoperability internally and externally.