Need a theological research project?

John Frame says:

So far as I know, nobody has ever made a serious theological study of the level of error that renders a church apostate, or to put it differently, the kind of theological differences that are tolerable or intolerable within a church body. I commend that study to theologians younger and more astute than I. I see this as a daunting task. Perhaps it is not possible to determine such levels objectively.

The Doctrine of the Christian Life (P&R, 2008) p435