Actual Question: “As you change the ecclesiology more towards a decentralized structure – how do you prevent that people would build their own kingdom and draw people out of the church?”
The best prevention against those who seek to do this is ongoing coaching. Calling leaders and their emerging teams to discover the biblical passages on themes like plurality of elders has proven helpful. Paul was always operating in a team setting and with appropriate mutual accountability. Calling all disciple makers into mutual accountability is foundational to multi-generational disciple-making.
There have been instances of what the questioner is raising which have happened in Movements. It often becomes obvious when they cease sharing the stories of breakthrough, transformation and the numbers of new groups being started. Tracking outcomes is critical to assessing health and leadership issues. Getting emerging leaders to do ongoing Discovery studies (written and/or group) is critical to helping them develop a strong, healthy biblical approach to leadership.
Encourage them to explore the leadership model of Barnabas. Spend time in Ezekiel 34 where Israel’s leaders are compared to shepherding. Explore the theme of “shepherding/pastoring” in both the Old Testament. Investigate the model of leadership Jesus establishes in Matthew’s Gospel. Mutual accountability in an ongoing leadership cohort (which maybe meets once a month) can be profound in protecting God’s people from self-serving leadership models. They are rampant in our world, so we must anticipate their will be challenges.
Who do leaders answer to, ultimately? That is the question they need to answer.