InfoQ recently published an article titled Debating agility at Thoughtworks, which follows an exchange of views about perceived religious entrenchment and dogmatism among practitioners of agile methods.
I guess some people might think me religious, especially after Gus and I wrote what we sarcastically called the Zealot's Handbook. I don't think it's far off the first edition of Extreme Programming Explained, but perhaps with the knobs turned up a little further than 10. I choose to follow the Zealot's Handbook because I produce better quality, achieve higher productivity and experience more fun when I do. I'm not religious about it. My choice is an objective decision made by an experienced person based on empirical results obtained in the field. I've been doing Extreme Programming for 6 years and in that time I've tried many variations and they've never been as successful as when I follow the Zealot's Handbook. This success is why I choose not to compromise my agility and why I avoid a pick and mix of practices.
I'm a person driven by my values: trust, courage, empowerment, accountability, respect, communication (including feedback) and simplicity. They are the heart of me. I'm a person guided by my principles and, in the context of software product development, I'm also guided by the principles of the Agile Manifesto and the principles of Extreme Programming and Lean. As such, the adaptations I make to gain improvement do not conflict with my values nor my principles. This enhances my agility. If the adaptations did conflict with my values or my principles, my conscience would wrestle with my actions and I would be at odds with myself. This would make me unhappy and my agility would be diluted to some agile mediocrity.