On any given Sunday during worship, I am playing two different roles. Those roles are sacrificial and sacramental, and you can tell the difference by the way that I am facing. It explains one of the questions that I get quite often from people who didn’t grow up in the Lutheran church, “why do you turn around to pray?” 
I turn around to pray when I am in “sacrificial” mode. When I am functioning “sacrificially” I am functioning on behalf or with the congregation, coming to God. So I face away from the congregation and to God when I’m doing these things. They include: making the invocation, confessing my sins along with the congregation, and praying on behalf of or with the congregation.
I face the congregation when I am in “sacramental” mode. When I am functioning “sacramentally,” I am functioning as the conduit through which God is giving gifts to the congregation. These things include: when I am announcing absolution/forgiveness, when I or the reader is reading the Biblical texts, when I am giving the sermon, when I am saying the words of institution, when I am giving benediction.
There is another sort of middle category when I’m facing “sideways”. These things include most of the time that I’m at my chair in the sanctuary. For instance, when we say the Creed is it neither a sacramental nor a sacrificial act, the same goes for when we’re singing the hymns and much of the liturgical songs.
Many churches don’t have this distinction of turning around, but for us, it is supposed to bring a clarity to what is happening. Having acted in high school and college, it is similar to the acting term of blocking. Blocking is the non-verbal situating of an actor’s body to convey what is being said. Bad blocking can ruin even the best delivered of lines, and good blocking can cover a multitude of sins. That’s why I turn around on a Sunday.
It reinforces a point that I feel needs to be made often, that when we worship, we’re not just using our minds. Our bodies are a part of our worship as much as our minds because Jesus didn’t just die for our minds (or spirits, or whatever other disembodied verbiage you like using), but He died for our bodies, bodies that will be Resurrected like His. So whether it is my turning around or your making the sign of the cross or even the simplicity of standing up and sitting down – our bodies are important because they were important enough for Jesus to die for. So when you see me turn around on a Sunday, you can think to yourself, “he’s acting sacramentally” or “he’s acting sacrificially” but you should always think, “my body is important. Jesus died for me. Thanks be to God.”