The Greek word εὐαγγέλιον (evangelion) originally meant a reward given to the messenger for good news (εὔ = “good”, ἀγγέλλω= “I bring a message”). In modern days, it actually refers to promoting ideas with actions, events and other socio digital schemes to spread the word about a new path breaking discovery, platform or app.

Volunteered (or participatory) Geographical Information is one of that good news. It is a recently coined term to define the use made of wikis, social networks and other platforms in order to create, gather and disseminate openly geographic information provided voluntarily by individuals. Many platforms, like Open Street Map (OSM), Crisis Mappers, gv SIG or Mapbox, allow users to create openly and discuss collaboratively to share their own contents and problems through the geolocation of features that are not initially shown in classical official maps or census cartography.
The most faithful community around a platform is that one from OSM, with more than one million users and 18 million edits. Their gospel goes beyond merely advocating against legal or technical restrictions to prevent others from using geo data openly. It commits to ground truth militancy, allowing us all to collect and use geo data for the common good of all in society. They usually demonstrate that sharing their faith with open mapping nonbelievers can be intimidating and difficult, but also incredibly rewarding.
There is a whole new generation of NGOs and initiatives evangelizing with innovative programs helping to promote OSM and teaching it to converted mappers. Programs like MapGive, Stats UP from GeoCensos community, Youth Mappers and School of Data show how well the contagion of evangelization is working for Open Street Map. The good news is here to stay.
As any kind of “announcement of the good news”, evangelizing on OSM needs to be carefully analysed, planned and launched to be effectively introduced to new enthusiastic users. A well thought and packed program can assure OSM – or any other platform for what it matters – attractiveness to the entire proprietary and open mapping ecosystem; i.e. official cartographers, statistical and cartographic offices, universities, humanitarian NGOs, local government and advocacy communities among many others.