That sounds like an awesome experience! Honestly, I’d say just sit back and let it unfold. Classical concerts have a way of filling the space with sound in a really immersive way, especially in a church setting. The acoustics can be pretty incredible. You might notice how the instruments layer together and how sound travels through the space. But I wouldn’t stress about critical listening; just soak it in and see what stands out naturally. Sometimes the best moments are the ones you’re not analyzing.
Let us know how it goes!