This question is interesting because it asks what is possible. First off we have to recognize that most religions deal with the impossible by man. Next thing we have to grasp is that 99% of those "enlightened" had a mentor, priest, guru, sensei, shaman, kahuna, monk, rabbi and the like to get to a point of really grasping human values.
So it is 100% "possible". And we have to really separate religion and spiritual aspects aside from religion.
there is also divine intervention.
And just for interest you put in the notion of "adherence" as opposed to simply having a faith in human values and principles.
Boy, show me one person who can live in strict adherence to human values. Many try and succeed 75% of the time, but most do not even get close to the percentage.
Yes it is possible and is happening every day with atheists. Funny isn't it that we use the term "human" values. Well that would not be the same as values from a God of religion would it. I have been taught human values by people and their religion had nothing to do with it. However my adherence to those taught human values is basically up to one person and not a religion.