Here is one attempt to explain "church" to those who have never been. 

In Perth, most people have never gone to church and most people don’t really know what it involves. So we would like to try and demystify it a little, by comparing it to a big family. Comparing the church to a family is an analogy that has been used for centuries and is usually very helpful. We call God our Father and we like to refer to other Christians as brothers and sisters. We have a similar connection, bond and responsibility to each other, as many would have with their own blood family.
Church is not a building, but the people. You could almost think of it as a collective noun for Christians; like a herd of elephants, a gaggle of geese, a swarm of bees and a mob of emus. It’s a church of Christians! Read our article here that elaborates the concept of church and the family.

My American History professor was a kind, serious and humble man. His mannerisms suggested he knew just enough. One day a clever classmate mistook his humility for ignorance. She began lecturing him, and it seemed she knew more than he did. He listened patiently and respectfully. When she was finished, he gently and quickly delivered the first intellectual knock out blow I had ever seen. Through a brief and gentle show of his intellectual capacity, my classmate was humbled into silence and a new found humility and respect. What we all realised is that he taught in this humble way, because he was speaking to chickens, not because he was one. His wisdom was far greater than ours. In our prior arrogance, we didn’t understand his humble teaching approach and couldn’t see his wisdom. Discover here on how often times God's wisdom is mistaken as foolishness in our own understanding.