Now, here is my disclaimer and my confession: I generally do not like Christians. There are a few that I have met that have been wonderful and I enjoy being around but invariably, I feel, there is a judgment thing going on with Christians. And I think that's part and parcel of the religion. Some Christians will say that God is the judge (when it comes to what happens to non-Christians after death) but then will also point to the "infallible" Word of God in terms of what happens if one refuses to accept Jesus as Lord and Savior. So, in other words, they *know* how God feels about things. The Christians I've liked and gotten along with so far will admit that they don't totally know the mind of God. They will acknowledge that there may be other spiritual paths just as valid as theirs.
And speaking as someone who grew up in a heavily Christian household, I know that I am biased against Christians and Christianity. I remember vividly being told when I was about 12 or 13 that yoga was basically evil. I wanted to ask questions but was silenced. It seemed as if anything that folks were ignorant about or that was different was called evil. Including (and maybe especially) our own indigenous religions.
But I digress . . .
Should Christians practice yoga? I guess that's something a Christian would have to seek God's face about. Yoga as it's presented in the West is a watered down version. It is indeed a whole philosophy and spirituality. Does that philosophy and spirituality stand at odds with Christianity? It depends on your brand of Christianity. But in my eyes, you can have a philosophy and a religion and the two might not be at odds. For example, you can have a philosophy of veganism and be Christian. You could ascribe to the philosophy of yoga and still be Christian. If you ate a vegan meal, I don't think that would cancel out or go against your faith? If you practiced yoga, I don't think that would go against your faith.
What is yoga anyway? I like this explanation the best. But yoga has also been described or defined as "union". I read somewhere that it is basically aligning yourself with God, the universe, etc. What I haven't read anywhere is that each pose is "in praise" of a different Hindu deity.
But isn't being a Christian simple? Isn't it to believe that Jesus Christ is the son of God, God Himself made manifest in the flesh, who came to die and whose blood is redemption and who by resurrecting on the third day conquered death and is now seated at the right hand of God? Isn't the work of a Christian to follow in Christ's path? It seems to me that yoga could be a legitimate way to work at your Christ-like-ness (for Christ exemplifies all the Yamas and Niyamas) and would not challenge your faith. To me, honestly, all these other add ons and rules that organized religions add on are just superfluous. Let's get to the root. Too many organized religions make it seem like there are 500,000 distractions (sent by the devil, of course) to get you off the narrow road. But according to the Bible, it's so simple to stay on the narrow road that a child could do it.
It's interesting how folks describe yoga as "new age". It's kind of like how "going green" is the "new black". I usually don't verbalize my thoughts on these things but it seems that all too often things originated by people of color are co-opted by White folks and given this new sheen, like it's the cool thing to do. As if there haven't been folks doing it forever and ever and ever. But what's more insulting is how so many times, there's not even a clear understanding of these practices and ways of being. It's not genuine. But be that as it may, it's what we often have here in the West. Many, many Westerners divorce the spiritual from the physical when it comes to yoga . . . so no, I don't see the problem with Christians practicing the physical aspects of yoga at all.
Well, I don't know if Christians should practice the spirituality of yoga (although it's been argued many times that there really is no separation) but I do know that if a Christian is interested, they should look to the root to get a real understanding of what yoga is just like they should look to the root to understand Christianity. They shouldn't rely on what someone tells them or what an article says. They should study. Be open-minded. Learn about it. And then see if it jibes with their own faith.
I ran across this blog which had some interesting insight.

it used to to actually get him down. And so, Chi-Chi, the confirmed early riser/morning person, is going to try working out at night. My sister suggested it and while I was resistant to the idea at first, it actually makes good sense at this juncture.