Today if you were to ask a person who is devoute to his faith, has an open mind and does religious studies, you can see clearly that they too will tell you religions have been changed and is not in it's original teaching. This is why I don't go to extreames such as sects or denominations.
Hang on here, aren't we getting a bit ahead of ourselves?
How exactly do you "change" a religion? There is a difference between a religion and what people believe
about that religion.
You're assuming people have an absolute grasp of what a religion is supposed to mean. But what if you have a religion that isn't concrete and set in stone?
To change a religion there would have to be some Book somewhere that can be changed, edited and modified. Where do you find that Book?
One might say this is obvious, that Jews have the Torah/Tanakh and that Christians have the New Testament. Yet even though they refer to the same texts their beliefs are diverse. It's as if throughout the centuries they have been speculating, discovering and rediscovering the true meaning of these texts.
If we say that the real religion is found when it's true meaning is discovered, that this is the "Book" that one seeks, then the Torah/Tanakh or New Testament are not really the "Book" that defines Judaism or Christianity. The real "Book" is either somewhere else, is invisible, or doesn't exist at all.
From time to time, I hear Jews speaking about some kind of "oral tradition." This, I believe could be regarded as Judaism's equivalent of a "Book," that there is no so-called "Book" in Judaism -- it's an oral tradition. For Christians, you could say the same thing. There isn't really a so-called "Book" in Christianity. What you have instead is what Christians call their "Messiah," their spiritual leader. Christians all around the world are speculating on what this messiah figure could mean for them.
I could say therefore, that the Torah/Tanakh is a text
about Judaism rather than one that
defines Judaism, and likewise, the New Testament
explains Christianity but doesn't
define Christianity.
If Jews and Christians want to "change" their religion, there isn't really a "Book" around that one can modify. Even if someone did change the Torah/Tanakh/New Testament, it doesn't change the religion. The real religion is something else entirely, perhaps even invisible. The words in the text itself is concrete and set in stone, but the meaning of the text is something that must be explored and inferred based on the subjectivity of one's knowledge and life experiences.
Moreover, there are so many identical copies of Christian and Jewish texts around that if you produce a changed/modified/corrupted version people will notice and simply use the original authentic ones and ignore the modified ones.