Because of the rise of modernity and the affect it had on the cultural perception of the gospel, many liberals abandoned the historical gospel and replaced it with a more "relevant" gospel. In the name of evangelism, liberals created a gospel that was unoffensive, and thus, unredeeming. The Emerging Church, I believe, is doing the same thing.
But J. Greshem Machen was the leading figure in the 1920's against the rise of Protestant Liberalism. I have read Machen's classic book Christianity & Liberalism (Part 1, Part 2) and it continues to influence how I think and engage liberal movements. But I knew very little about Machen.
Recently at a conference at the Southern Baptist Theological Seminary, I had the opportunity to listen and to meet DG Hart, scholar and historian. I was impressed by how well Hart understood Machen and was interested in reading what he had written regarding this important man. Therefore, I picked up his book, "Defending the Faith: J. Gresham Machen and the Crisis of Conservative Protestantism in Modern America."
Hart not only survey's the life of Machen, but looks at who Machen was, his theology, his philosophy, his critique of liberalism, and even his politics. This is the work of the scholar, therefor,e it includes concepts and has a writing style for scholars. But for the most part, even the average person could pick up this book and read it.
One of the things that struck me was how Hart discussed Machen's view on engaging the culture. In Christianity & Liberalism, Machen rightly points out that liberals went wrong whenever they accommodated to the culture which was, at that time, modern. But the question arises, how then do we engage culture without corrupting the gospel?
Oftentimes, those who speak negatively of the culture are viewed as being anti-culture as if we cannot be affected by the culture, like the Minnonites. But that is not the case, and Machen is a good example of this. Just because Machen was critical of liberalism and their love affair with modernism doesn't mean he was a hermit. Machen was actively involved in politics, which I found really interesting. Machen publicly endorsed a candidate for President, who lost in the election, and continued to have strong political beliefs. For example, Hart details that Machen was a libertarian in economic policy.
Machen was very much engaged with the culture he was surrounded with, but he refused to hand the gospel over to it, let the culture corrupt it, and essentially abandon the saving grace of Christ. Machen, as I learned through Hart, is a wonderful example of someone who although critical of the effects of the culture on the faith, was at the same time very much involved in the culture, not just as an academic scholar, but as a believer trying to make sense of doctrine and reality.
I highly recommend Hart's book especially for someone interested in the debate between liberals and conservatives. I also encourage you to read Machen's book, Christianity & Liberalism, for although it was written almost a century ago, it is still applicable today.