If we look up the word “church ” in a regular English dictionary it will give you the most widely used meaning first, which is a building or house of worship. We have to look down the list of alternate meanings to find one that refers to the people in the building. It’s one of those cases where through common usage the primary meaning of the word has changed from what it was originally. Here’s how that happened.
The first believers met in homes. As their numbers grew they began to use structures intended for larger gatherings. When these structures were built specifically as a meeting place for the congregation they were correctly called church buildings. As time went by this was shortened to church, and for most people today the word “church” refers to the building.
But if we go to a Bible dictionary and look up “church” it will say the English word comes from the Greek word “ekklesia”. In the general sense, ekklesia means “an assembly of people, called out of their homes into a public meeting place.”
When applied to Christians, it refers to those people who are called out of the world into a relationship with Jesus Christ. Therefore, in the Bible the word “church” always refers to the body of believers who have given their lives to the Lord, and not to a building in which they may be gathered from time to time.
When Jesus said, “I will build my Church” in Matt. 16:18 He wasn’t talking about constructing a building. He was talking about creating a world wide body of believers.