I`m going to say something a lot of people probably won`t like, or agree with, but here it is anyway.
FWIW.
I`m not sure that criticizing "new agers" or attempting to point out their short comings would make them see the light, or would make them stop doing what they are doing.
And I`m not sure that interfering with their "lessons" at this time, is even the right thing to do.
Some people see and have seen the "errors" of their thinking but until "they" do nothing much will change.
Many people have followed a wrong path in the past and many more will in the "future".
There isn`t a lot of hard evidence that the early Mayan cultures were at all into these blood "sacrifices" and what is assumed about that is pretty much centered around the stories of some "star god" or gods.
Realistically, people arn`t just going to wake up one morning and say hey, "it hasn`t rained in awhile so lets rips some hearts out and see if that works."
So if you think about it, this more or less implies that the people thought the "god" either didn`t have the ability to bring rain, or that the "god" was a psychopath... and that some blood and pain would make him happy enough to respond.
And the very fact, that the people "were taught" some amazing things about astronomy, stone workings and all else they learned during this time, does not imply.. to me anyway.., that the "god" was an inanimate rock that fell from the sky, but was an actual walking, teaching entity of some kind! And a fallen rock need not promise to return one day in the future, since it is already here.
So, something out of the ordinary life experience was occurring with these people.
And with the Sumerians, the Egyptians, etc.
It would seem that blood letting sacrifices, of any kind, to any god, is a sure sign of the impotence and the true "negative" nature of the god, the ultimate slavery of the people to the god... and the failure of the people to understand that.
This is evident even today with the present gods of "religion" such as it is.
Does it seem that on the other hand, gods of "creation" would teach nurturing, compassion and the ability to obtain from natures bounty without ripping your neighbors heart out and "glutting heavily" in the destruction of other people, or the world?
These "new age" people of the coming "new age" are simply seeking a god of their own, sadly... any god...to attached themselves to, and who might give them power over others.
Over Nature.
And it seems to me that they are spiritually "about the same" as those later cultures who fell for the power, or the gods ...outside...of themselves, who eat the world alive.
All this has nothing to do with taking a piece of "indigenous ceremony" and adding some Celtic ritual, while throwing in some Asian theology.
I really think it has to do with being a "new" kind of people who have not learned the lessons of the past and are destined to repeat those mistakes all over again in the coming ( new age ) or long cycle.
Sorry for the long winded essay here, but the point is that, I don`t see that there is anything a person could do to change their minds or set them on a better path.
They have their destiny and they are following their "hearts" to it, for all intents and purposes.