Vater unser im Himmelreich, BWV 737

"Of the various organ arrangements Bach made of this chorale, this is the most subdued. The piece is written in stile antico – the ‘ancient’, vocal, polyphonic composition style of the sixteenth century. Bach may have used the ‘ancient style’ here to emphasise the fact that Vater unser im Himmelreich is a prayer. And a prayer implies words and thoughts, either spoken or sung. In fact, this arrangement is a four-part motet in the ancient style and you could easily perform the whole piece in song. Occasionally, there is a slightly more daring harmony, which is all that betrays the fact that this piece is not really a motet from Luther’s day."
Source: All of Bach