The English Oxford Dictionary defines Dogma as...
A principle or set of principles laid down by an authority as incontrovertibly true : 'the dogmas of faith'
To apply this to the agile world we only have to look at the Principles behind the Agile Manifesto. These principles are guidelines for good practice. If Agile, in it's purest form, was a faith then these principles would be akin to Christianity's ten commandments.
The principles are based on experience and growth from many different business types using many different techniques over an extensive period of time. In this Agile is less like a faith and more like a science. It is in the latter that true agility can be found, not in the former.