First, we must understand what church is - church is wherever God meets with a group of His people. That can happen at a riverbank, in the wilderness, and even in a building! But the two important elements are (1) God's people are gathered together, and (2) God is present there.
The Bible has much to say about "How" we do church, but our questions is "Why?" Well, we've sort of already answered that. First, God made us for community - to help, love, encourage and build up each other. Secondly, God made us for Himself, with a spiritual void only He can fill. Psalm 63 speaks of metaphorically "looking at" God in worship, seeing His power and glory - comparing it to food and drink for thirsty, starving souls.
So, that's our mission here at Providence - to be a place God can gather together with His people. Come experience it for yourself.