I’ll throw a log on this fire, but it won’t be about them per se, it will be more about you.
What is Agile to you? What is Agile to him/her? What is Agile to the team?
One cannot be a non-believer in something unless everyone agrees to what they’re assessing.
I worked with a non-believer, so to speak. After talking with them, they were actually a firm believer in what I consider to be Agile. Not because of anything I did beyond dispelling what I consider to be misconceptions the person was introduced to by others.
“We don’t have to do documentation,” they said. “Not true I responded. It’s just that, at the end of the day a user can’t live in a blueprint the way they can a house.”
“It’s just a marketing scam, we’ve been doing iterative development forever,” they said. “There’s some truth to that. But, it gives us a common vernacular to differentiate the mindset from others. Even Pragmatic Dave Thomas, one of the drafters of the Manifesto has a talk decrying this part of things. That’s other people and not us though.”
After a while they stopped talking about how terrible Agile is and started talking about the way development should be. At the end I said, “You do realize you almost quoted the Manifesto verbatim and outlined the Kanban framework?”
Having said that, if the person honestly doesn’t want to work with other humans and the product or team demand that you do...they might not be right for that product or team.