Of all the various movements that have affected the evangelical Christian Church in the early years of the 21st century, the young, restless and reformed or 'New Calvinists' are among the most significant. Jeremy Walker acknowledges the difficulties of tackling this subject, which he approaches with some caution. He writes of his desire to provide 'a balanced and appropriately irenic assessment' as he considers the contribution of various personalities:
"At the core you will hear names such as John Piper, Mark Dever, C.J. Mahaney, Al Mohler, Mark Driscoll, Matt Chandler, Kevin DeYoung, Ligon Duncan, Tim Keller, Don Carson, and Wayne Grudem. On the websites and in the blogosphere names like Justin Taylor and Tim Challies are prominent. More on the fringes, and with a much more ambivalent relationship, are men like R. C. Sproul and John MacArthur on the one hand and James MacDonald and Francis Chan on the other."