The Lubavitcher Rebbe wrote the following letter:
By the Grace of G-d
It is well known that certain oriental movements, such as Transcendental Meditation (T.M.), Yoga, Guru, and the like, have attracted many Jewish followers, particularly among the young generation.
In as much as these movements involve certain rites and rituals, they have been rightly regarded by Rabbinic authorities as cults bordering on, and in some respects actual, Avodah Zarah (idolatry). Accordingly Rabbinic authorities everywhere, and particularly in Eretz Yisroel, ruled that these cults come under all the strictures associated with Avodah Zarah, so that also their appurtenances come under strict prohibition.
Moreover, the United States Federal Court also ruled recently that such movements, by virtue of embracing such rites and rituals, must be classifies as cultic and religious movements. (Of. Malnak V. Maharishi Mahesh Yogi, U.S.D.C. of N.J. 76-341, esp. pp. 36-50, 78)
On the other hand, certain aspects of the said movements, which are entirely irrelevant to religious worship or practices, have a therapeutic value, particularly in the area of relieving mental stress.
It follows that if these therapeutic methods – insofar as they are utterly devoid of any ritual implications – would be adopted by doctors specializing in the field of mental illness, it would have two-pronged salutary effect: Firstly, in the view of the fact that these methods are therapeutically effective, while there are, regretfully, many who could benefit from such treatment, this is a matter of healing of the highest order, since it has to do with mental illness. It would, therefore, be very wrong to deny such treatment to those who need it, when it could be given by a practicing doctor.
Secondly, and this too is not less important, since there are many Jewish sufferers who continue to avail themselves of these methods though the said cults despite the Rabbinic prohibition, it can be assumed with certainty that many of them, if not all, who are drawn to these cults by the promise of mental relief, would prefer to receive the same treatment from the medical profession – if they had a choice of getting it the kosher way. It would thus be possible to save many Jews from getting involved with the said cults.
And another letter
Inasmuch as the Torah and mitzvot were given to all the Jews, and to each one individually, for all times and in all places, and “these are our lives and the length of our days,” it is clear that every moment of a Jew's life should be consecrated to Torah and mitzvot. Hence it is both surprising and painful to see a Jew spending precious time in search of "greener pastures" elsewhere, even if his intentions are good, for, as above, the important thing is the actual deed.
Needless to say, the above includes Yoga and similar cults even if it is not connected with anything pertaining to avodo zoro (idol worship) - if there is such cult that is completely free from avodo zoro, and in this only a competent Torah authority who is permeated with halocho is qualified to rule.
I am not seeking opportunities to admonish anyone, but since you mention certain oriental cults, it is my duty to call your attention to the fact that every spare moment that a Jew can use to deepen his knowledge of Torah he dissipates it on other things is deplorable enough, not to mention cults that in their overwhelming majority are certainly connected with avodo zoro in one way or another, and if there are exceptions, one must make doubly sure through an expert Torah authority, as mentioned above.
The present days are highly suitable for Jews to separate themselves from any alien influences in preparation for the Festival of Mattan Toraseinu (the giving of our Torah), when G-d sanctified us as a nation apart from all other nations, a unique "Kingdom of G-d's servants and a Holy Nation," by giving us His holy Torah and mitzvos. And since G-d Himself has shown us the way, what sense is there in looking for better ways. This is really too plain and self-evident to need further elaboration.
Wishing you a Joyous and inspiring Festival of Kabbolas haTorah and the traditional blessing to reaffirm the commitment to Torah and mitzvot with joy and inwardness.
The Rebbe’s Signature