Ref21 has posted an article by James Torrens on the self-defeating reality of pragmatism. Torrens writes:
This uncontained pragmatism ('what matters is what works') is used to justify all kinds of strategies in order to 'advance the gospel' or 'build the church', without any thought as to what kind of gospel is being advanced or what kind of church built.
For example, in some circles, the Homogeneous Unit Principle (2) is a popular strategy for church growth. It's popular because it works. It's popular because we all feel more comfortable surrounded by people who look like us, think like us, and behave like us. But is it biblical? Paul's vision of the church in Ephesus and the picture painted for us in Revelation suggests that it is not.
Similarly, particularly in the bigger and 'broader' denominations, it is common to hear people argue that unbiblical beliefs and practices ought to be tolerated, either for the sake of unity or for the opportunities for gospel ministry that being part of such a denomination affords. This is essentially a pragmatic approach to heresy and apostasy. But, as is becoming increasingly clear, one cannot successfully defend the bible by letting the bible slip from one's hands.
To expand, one cannot defend biblical authority if, in seeking to do so, one ignores and thereby undermines the authority of those parts of the bible which give clear instruction as to how to handle, for example, a persistently unrepentant brother. This kind of pragmatism is ultimately self-defeating, for justifying the unbiblical means (by appealing to a positive or 'biblical' outcome) will ensure that the outcome is in fact far from positive or biblical. What eventually happens, to borrow Paul's metaphor, is that the yeast spreads through the whole loaf: the situation worsens, rather than improves.