Recently I have been thinking a lot about Vision, and it's implications on Unity. And the more I think about it, and look around for examples, more I am sure that Vision has great implications concerning unity.
The church must be united. We are all one body. God has given a global vision to his church. But at the same time, God has created great diversity in the world, and gives different visions to different people. All of those visions together fulfil the global vision: build the Kingdom of God. And that's all very well, but it is a utopia to think that we can be in the same small community with people that have different visions and missions.
Let's put this into a formula. The greater the difference between the vision God as given to two different people/groups, the greater the distance between those two people/groups should be, in order to maintain unity.
I know, it seems a contra sense. But think about it. If one has the mission to reach teenagers, and the other elderly people, they can never really be in the same small group. Neither of them would be able to fulfil their purpose in all its fullness. The ministry of one will hinder the ministry of the other. They will be able to have synergy concerning more global events, but never in a very small environment.
For that reason, when you start a house church, it is of utmost importance to be sure that you are all with the same vision. If you are not, everyone will start compromising, and all of us will be very far from our potential.