Almost all “traditional” churches are heretical, dead, and full of unbelief. They include churches from every human tradition, such as the Reformed, Presbyterian, Baptist, Methodist, Anglican — all of them. There are cases where I will not support someone’s decision to leave a church, but it is often understandable, even commendable. Many churches should not exist. Instead of improving themselves, they use tactics of terror and control to keep their members from leaving. It takes spiritual courage and commitment for one to extract himself and his family from such places.
When several Christians join together, they indeed constitute a church. Things like seminary degrees and denominational ordinations are human credentials that often help church order but are never necessary. However, this does not mean that every Christian is qualified to start or lead a church, but it means that no Christian is forbidden in principle. These groups are indeed churches, but only sound doctrine and divine power make good churches. Some groups are likely to be worse than the churches that they have abandoned.
Even though many leave for incorrect motives and reasons, instead of making it a matter of doctrine or policy to condemn and threaten them, traditional churches should repent, and fix themselves. If people return and get more of the same death, unbelief, and church politics, they will just leave again. And this time, I hope, they will know better than to come back.