Hello Diane,
I will speak from my own experience:
When I started doing yoga, all I was interested in were the asanas.
I started with Ashtanga yoga - primarily focusing on a “workout” in a nicer, more peaceful setting than a gym.
I was not open or ready for any spiritual message then. If my teachers would have focused on that, I would have probably quit going to yoga, fearing someone wants to get me into a sect ;).
However, slowly, through practice and gentle subtle side notes of my teachers (“it’s not about competition, just stay with your breath,…”) I noticed the benefits of yoga. Through asanas I was able to come to a peaceful place in my mind and heighten my awareness.
My own experience showed me that there was a lot more to yoga then just movement of the body and I opened up to find out more about the different layers of yoga.
My point is: I think especially with beginners or people that were sent to a class because of issues in the body - I would focus on the body. I would not get into too much spirituality. Eventually the student may experience it: that doing asanas can act as a gateway to access mind, intellegence and eventually universal spirit. That’s the great thing about yoga: it’s a technique that can be taught and the interpretation of the result is up to the student!