For long term yoga practitioners: do you feel you're contacting evil spirits?

I have been reading a Christian website and some of them are convinced that, if a person keeps doing yoga, they are able to somehow contact Evil Spirits and come to some knowledge of them. So many Christian churches are warning their members to turn away from yoga. I don’t fall for it. If I can contact the World of the Unknown I’m all for it if it doesn’t harm me. Is there any truth to this? Is it unexplainable? How can stretching cause us to rub elbows with other worlds, even evil ones? Fascinating!