Washer is addressing far more than the progressives and cults as it would appear to many those churches teach false doctrine as even seeker and Charismatics believe this.
I used to be in the Covenant Church and even they would denounce the groups I mentioned. The Covenant Church held to many false doctrines and it took getting to be in their church to discover this.
I cant find any evidence of another gospel. They do ordain women and have women pastors which is a unbiblical practice, but I am not going to write them a letter over this one.
I was listening to Todd Friel the other day and thought of you. He was quoting Spurgeon and many others on their usage of the Law in evangelism. I wanted to remember the message and link, but I cannot recall it at this time as I was working. I apologize! But the quotes he used were awesome, and supported the usage of the Law in convincing the lost of their state before God. He quoted many men of God on this, one after another.