An important question in a world where many claim that "this" is the "true church" and "these" are the "marks" of a "true church". In asking these questions we miss the wonderful reality that wherever you find God's people, that is where you find the church. A church not reliant on ordained men or religious rituals or the acceptance of the world. God's church is found among God's people and nowhere else.
Check out this great post from Aussie John quoting J.C. Ryle, CAESURA: THE TRUE CHURCH- Part 1