In this case, が is incorrect because you are conveying a known piece of information. When you describe a known or general fact about a subject (お寺), you have to mark it with は, making it the topic of the sentence.
The temple is next to the park.
(This is a known fact to you.)
Birds can fly.
(This is a general fact.)
This とは is a simple combination of two independent particles. This と is a particle that marks a comparison target. This は is the topic/contrast marker. As you may know, the topic marker can directly follow から, まで, に, で, etc.
How is と used in these sentences? (See the last half of Chocolate's answer)
What about this combination of と and や
If you haven't ...
「って 」is an informal equivalent of 「というのは」.Therefore, it is used in the same situations than 「という」in spoken spoken language rather than written.
"What doesトロ mean?" or "What is トロ?"
When using informal speech, the は particle is sometimes ommitted, and that's why you don't see it in your sentence either.
In this case, というのは ...
The object of a verb is usually marked with を, but when that object is the topic of the sentence, を will be replaced with は. This is a basic grammatical rule, and it has nothing to do with the usage of 通して itself. See: What is a topic prominent language?
In your example, みなさんのパフォーマンス is the topic of the sentence, so it's marked with は even though it's the ...
I believe this usage corresponds to the following definition of 通す/徹す from 大辞林:
So ~を通して聞く would basically be "listen to 〜 straight through, from beginning to end."