In a church what is the ambulatory?

The plural noun for church is churches.

In the christian belief, it isn't the building that is the church; A church is the body of believers, who meet within the building.

No, Orthodox churches are where persons of Greek or Russian Orthodox faith worship. Like the Church of England, the Orthodox also separated from the Roman Catholic Church on matters of doctrine.

Well, in some churches the secretary does make an agenda for the church programs. Some do not. It really is just a matter of what the terms of employment are.

Church of God in Christ (COGIC) Church is not an Apostolic Church.