Early marketers of Apple products were known as evangelists. Guy Kawasaki, hired by Apple in the mid-1980s, developed the strategy of corporate evangelism, which he describes as using "ferver, zeal, and anything else to convince software developers to create Macintosh products" (Levy, 2000, p. 162).
Kawasaki (1990) describes the process of evangelism:
When you sell your product, people use it. When you evangelize people, they get infected, carry the torch for you, share your heartbeat, and defend you against your enemies. When you look in their eyes, you see your logo. (p.99)

This idea of Mac evangelism has continued and spread. Diehard Mac fans do indeed "defend" Mac against its perceived enemies: Microsoft and IBM in particular.