I found this post to be DEAD ON,  and is the main reason why The Church of the Saviour is such a model of mission and spirituality.  They totally redefine the meaning of the term “discipleship” from what it has become in “devotional/Bible Study” groups usage of it. 

Gordon Cosby, the leader of Church of the Saviour in Washington, D.C., noted somewhere that in over sixty years of ministry, he has never seen that groups which are formed around a non-missional purpose (prayer, worship, Bible Study, etc) ever ending up becoming missional. It was only those groups which intended from the start to be missional (and usually embraced things like prayer, worship and Bible Study) that ended up doing it.
This corresponds with my own experience. It is impossible to calculate how many people have contacted me over the years with a request to get involved in our work in Swaziland. Usually the conversation goes something like this: “Hi, we are a cell group / Bible Study group / prayer group from xyz congregation and we have heard about your work in Swaziland. We feel that it is important for us to reach out to others and we would like to visit you to find out how we can assist you.”
Being a fairly positive person, I always invite them to come, but at the back of my mind I know that there is a more than 90% chance that nothing will come from the visit. The reason is simple. To be part of a cell group or Bible Study group asks a small investment of your time: 1 – 2 hours per week. And let’s be honest – these meetings are fun. Coffee and cookies are served. There’s a lot of time for interaction. And after worship and prayer you feel revived and ready to tackle the rest of the week.
Involvement in mission asks much more than that. On most Sundays I leave home at 8 in the morning and return home somewhere between 2 and 3 in the afternoon. And that’s just for a church service. Anything happening during the week involves a lot of driving – two hours at the very least – entering places which may make you feel uncomfortable, seeing things that are not nice to see, walking in the scorching sun. After their visit these groups have a lot to say about their experience and always promise to come back again, but more often than not we never hear from them again. They will return to their cell group / Bible Study group / prayer group and will probably never return to Swaziland.
If I have to say why this happens, then it boils down to a lack of vision. A group that is formed without a missional vision, will never be able to become missional. They will merely follow their vision and if it is not a missional vision, they will not become missional.

Can a non-missional group become missional? « Mission Issues