First of all, the practice of yoga is more than just stretching exercises. The Catholic Church has never opposed stretching exercises but has spoken out against yoga. And regarding demonic possession associated with yoga, I trust the first-hand experience from actual exorcists (Fr. Gabriel Amorth, Fr. Chad Ripperger) who have seen it happen.
There are different types of yoga. The “stretching exercises” yoga is called hatha yoga. I went to classes in the 1960s and they never taught anything to do with philosophy or religion.
If there is anything “weird” about it, it would do with a medical system in India, and its concept of what causes disease and keeps people well – this may or may not be taught along with those “stretching exercises.” The West also had an ancient medical system based on the 4 humors, and other such ideas. We prefer modern Western medicine, because we perceive it as more effective, not because it is Christian. However, some people perceive that non-Western medicine and medical/physical practices are more effective, at least for some conditions, or in conjunction with modern Western medicine.
As for yoga being against Christian precepts, you may be referring to kriya yoga, which involves meditation, which (according to Wikipedia) is “intended to rapidly accelerate spiritual development and engender a profound state of tranquility and God-communion.”
I also practiced that for a couple of years sometime after I had left my Protestant church and before I became a Catholic. I wasn’t very good at it, nor am I very good at Carmelite contemplation now (which does not have any technique). In any case, this kriya form of meditation is NOT dangerous and the version brought to the US strives to include Christian ideas and in that respect is not very different from Christian meditation. Hinduism, unlike Judaism and Islam, has no problem with incarnation and Jesus being God.
BXVI before he became Pope only critiqued non-Christian forms of meditation for not involving the knowledge that God is within us; he mistakenly thought their idea was that God was outside the person. However, the Hindu concept is that God is within people, which is why when they greet people they press their hands together as if in prayer. Hinduism also has at least 2 vastly different concepts – monism or advaitism, that all is One, all is God; and dvaitism, that God is separate, which would be somewhat more similar to the Christian idea.
As for spiritual detachment. In Hinduism they only stress detachment from material and ego things. In Catholic Carmelite tradition, St. John of the Cross also stressed detachment from these AND from any spiritual blessing or experiences one might have had (and NOT to seek these). In that way this latter tradition is safer, since 1. the spiritual experience may not be from God, could even be from the Devil; 2. even if they are from God, one could become attached to the spiritual experiences, seeking those (which are quite comforting, pleasing, and could be a source of pride) and forget God, the true focus. So in that sense, perhaps Hindu and other forms of meditation could be dangerous and Carmelite meditation safe.
But this has nothing to do with hatha or “stretching forms” of yoga.
It is interesting that for a very brief time I tried a little qigong and tai chi (Chinese health exercises), which apparently was brought to China from the Indian Himalayas through Buddhism. I saw short program on TV about it, featuring one of the great qigong masters in China – who happened to be a Roman Catholic.
Of course, Catholics have to be very careful and cling to their Church and fellow Catholics, if they DO NOT read the Bible or other Catholic official writings much, for they might easily be led astray.
Because I was a Protestant and dabbled briefly in those Eastern forms, and later taught World Religions, I pretty much know the differences, and would be in a safer position to follow their exercises…up to the point where they may go against Catholicism.
