The following is excerpted from Mike Breen's blog...

This is what I believe:

• I believe there is inherent value in gathering a large group of people (75+)  together to worship God, submit to the scriptures, tell stories of God moving in the community, share the Lord's Supper, etc. We gather because, with one voice, we choose to worship our Risen Lord. We gather to be reminded that we are part of his story - his present and future Kingdom. And we gather so that we can scatter as missionaries to a world that is broken and in need.
• I believe the value of worshipping God together as a community is enough on its' own. If there was not one single person who wasn't a Christian in attendance, it would be just as important for us as believers. Worshipping Jesus for the sake of Jesus must always be enough.
• I believe that to sustain the scattered mission of the church outside of the large gathering there is the need for regular and rhythmic times of gathering together to remind us of the bigger story we are in, reinforcing why we live the missional life we do. I'm not saying it's impossible to sustain Kingdom mission outside of it, but it's very, very difficult. We gather, we scatter. We gather, we scatter.
• I believe the worship gathering exists first and foremost for believers, for people who are intentionally growing in their relationship with Jesus. Yes, people who don't know Jesus yet can come, but honestly, they aren't our top priority in a worship service. Can they come to faith in a service? Yes. Should we provide opportunities for them to step more fully into a relationship with Jesus? Yes. Can a pre-Christian benefit from experiencing the worship of believers? Absolutely. But we need to understand that if the worship service is our primary place of mission we've already lost the battle. We may believe in the priesthood of all believers, but do we believe in the missionhood of all believers - outside the 'gathering'?
• I believe the worship gathering should always keep an eye on the shaping of the community for mission outside of the walls of the service. When they leave the gathering, believers should know they leave as missionaries and agents of the Kingdom. How is the church community shaping that reality for people?
• I believe many who say they are advocates of the  "missional church" have thrown the baby out with the bathwater and have rejected, out of hand, larger gatherings. To an extent I understand this, but the reality is that many missional churches struggle to grow, stagnate and fizzle out. Why? Because scattering is unbelievably hard and gathering sustains. It reminds us who we are. It shows us we are part of a bigger story that is reinforced when, upon looking around, we see enough people to remind us we aren't alone in this. We hear stories of victory and redemption. It nourishes our souls and allows the wounds of the missional frontier to receive some healing. It is not the only place care happens, but it is an important one.

Humans are creatures of overreaction. We jump ditch to ditch quite easily. Many saw the issues and the inertia involved in becoming a Sunday-centric, worship service oriented community (and rightly so!). But know this: The reason the worship service became the center of evangelism and mission is because we stopped making missional disciples who understood the nature and purpose of scattering. We're bad at discipleship and so we've gotten ourselves into this predicament. Scattering is the cake and gathering is the icing in the life of the church. We've become a fat church from eating a lot of icing. But don't throw out the icing! Cake just never tastes quite  as well without it.

http://mikebreen.wordpress.com/2011/10/17/why-im-not-using-the-word-attractional-anymore/