Discipleship Is Messy
Having lost a connection to the wider church, many doctrines morphed. As the scholar Hayao Kawai noted, for the hidden Christians, "Mary ascended to heaven and became the intermediary, and Jesus, the savior," so that "the Trinity consisted of Father, Son, and Mother (Holy Spirit)."
So, yes, insider movements can go awry. But not if they stay connected to the global church. When Japanese Christianity came out of hiding in the mid-1800s, 30,000 secret Christians came out and the majority rejoined the church, renouncing unorthodox beliefs and practices.
How do we connect with, say, Muslim followers of Isa deep inside a Muslim culture? There are no easy answers—to reach out publicly would invite serious problems for the local believers. Here's where the missions community might give us wise guidance. One idea: Can some ministry organize mediators to connect by e-mail insider leaders with churches elsewhere to offer mutual encouragement? Surely in a digital age, there are ways to facilitate this type of fellowship.
God does indeed watch over his church, in its manifold expressions and during periods when believers are confused and immature. And he uses the global church, when we all stay connected, to help us "all attain to the unity of the faith and of the knowledge of the Son of God, to mature manhood, to the measure of the stature of the fullness of Christ" (Eph. 4:13, ESV).