I can't resist this quote from John Howard Yoder, which is cited in David Fitch's blog on mission and ecclesiology:

The political novelty that God brings into the world is a community of those who serve instead of ruling, who suffer instead of inflicting suffering, whose fellowship crosses social lines instead of reinforcing them. The new Christian community in which the walls are broken down not by human idealism or democratic legalism but by the work of Christ is not only a vehicle of the gospel …

Here's a very brief overview of church history, engagingly presented by Dr. Patrick Keifert, that focuses on missional church issues.

From Craig Van Gelder's book The Ministry of the Missional Church: A Community Led by the Spirit:

The church is.
The church does what it is.
The church organizes what it does.

The interrelationship of all three aspects is important to understand. The church is. The church's nature provides the framework and foundation for understanding the essential character of the church. The church does what it is. The nature of the church establishes the foundation for understanding the purpose of the church …

By Mary Sue Dreier

Missio Dei (Latin for "mission of God") has become one of the catchphrases of the missional church conversation. The phrase itself has a story to tell which illustrates the insights, importance, and implications it has for our future as a church in mission.

Missio Dei was coined to express the essence of the conversation when Christian churches from around the world gathered in 1952 in post-World War II Germany (Willingen) for an international council on mission. The twentieth …