Moderators are are from avast there are others that are avast Team, those from different departments like the virus labs that also post and some of those will also be evangelists.
An evangelist (and its different forms) is someone with more than 300 posts, it is just a forum status and means nothing other than that. They are more than likely to be avast users just like yourself and not avast staff.
See image, it is slightly dated now, from May this year.