This comment is related to the topic --the historical validity of Mahayana texts that has been recently been discussed, but I wanted to take it in another direction, and I am never sure if I should shoot of in another direction when this action may derail the train--so to speak. Maybe I will get that figured out by my 100th post on the forums.
For my job I need to consider all religions and how their sacred texts arrive and evolve. One thing I have noticed overall and also I have noticed this is regards to Mahayana texts it that texts seem to evolve according to what people need at a particular point in their development. And by development I mean their development spiritually as a group. Sacred texts arise to solve problems and needs that arise from earlier texts and teachings, or they arise to fulfill a need of the community at that time. So, perhaps the texts do not reflect "exactly" what Buddha taught, but they do reflect the possible implications of Buddha's teachings. What I mean is -- the Buddha taught to be island unto oneself and to discover truth and understanding not by what is revealed by what is realized. Although as a Theravada practitioner I interpret this one way, a Mahayana practitioner may find realization comes through one's relationship with celestial Buddhas (for example, I am guessing as I do not know).
Back to original point.
I wonder if it wasn't realizations in part that drove the creation of the Mahayana texts. They are valid, because they can help us reach liberation. Teachings that help one reach liberation was a big concern of Buddha. Validity is not just defined by being historically accurate but in their usefulness. Or we have to differentiate and say ok, this is not historically accurate, but it sure is effective and helpful for realizing the purpose of Buddhas teaching!
The Buddha would agree, I think. So, we can ask questions based on what can be scientifically proven and we can evaluate the validity of texts by their ability to support believers, and in the Mahayana case -- by their ability to help practitioners reach liberation.
I am not trying to prove anything but share what I have been thinking about recently in regards to sacred texts and how they change and evolve.
An example might be found in art --in early, early Buddhism images of the Buddha were symbolic, such as a foot print or a wheel, they did not represent the figure of the Buddha, but after the Buddha's death images of Buddha sitting, and lying ...began to be seen. Why? Some scholars say that is was because the people needed the figural reassurance found in representations of the Buddha. Years and years were passing since his death, and by seeing images of the Buddha, people were less apt to forget. Does this make the represented form of the Buddha not valid, because it developed later based on people's needs and not based on the time of the Buddha, I don't feel this is so.
Having said this --the sheer immensity of the Mahayana texts have, historically, put me off as being overwhelming.
Yet, I really do not want to deny their validity in being able to help people reach the goal, unless, I see for myself and know they are not helpful. I hope that makes sense.
I am daunted by Mahayana, comforted by it, and am open to it, but I seem to be able to access Theravada more clearly and easily at this point. Sher