by the 1970s the opc had grown a new ‘pietist/revivalist’ wing under the influence of jack miller. according to tim keller, the new life churches and their sonship course represented classic revivalism, and it did not fit well with the more doctrinalist cast of the opc. the new life churches were made to feel unwelcome and nearly all left in the early 90s to swell the pietist ranks of the pca.