There is no formula for Christian life – extremes are corrupt, and the middle ground is slippery.
-thus Bruce Charlton.
There is a human tendency for the means to become the ends. I suspect its because most means require submeans, and on a day to day basis the submeans are what require the most adjusting and evaluation. Which means that on a day to day basis, you are functionally treating the means as the end to be achieved. That being so, it is easy to forget the bigger picture.
What Dr. Charlton calls correctness, or even what He refers to as ultracorrectness, is a help to most people. Most of us, maybe all of us, need what we get from obeying in exactness. The path is always strait. But the straitness of the path isn’t what defines the path. It’s the destination.
I believe the theological liberalism for most people probably starts innocently enough as a means to correcting the problem of pharisaism and “ultracorrectness,” but it soon also becomes an end in itself and therefore a poison.