On the one hand, they assume that striving for sanctification undercuts justification by faith. On the other hand, in the Protestant approach to the Christian faith there is no real need for emphasizing growth in sanctity. Once you have accepted Jesus as Savior and Lord, your salvation is assured. Fundamentalist, salvation is absolutely assured. And that's it.
All beliefs have consequences.
The Protestant lack of an imperative toward sanctity has had consequences. One was brought to my attention years ago, when I was a student at Union Theological Seminary in New York. One of the visiting professors was Douglas Steere, who was a Quaker. After two or three days' work in the library with his bibliography, I went to his office. I'm not interested in what the Catholics have to say about prayer.