The Sermon on the Mount and Human Flourishing: A Theological Commentary, by Jonathan Pennington (Grand Rapids: Baker Academic, 2018).
I’ve been using this book as my main helper while preaching very slowly (because very occasionally) through the Sermon on the Mount. When my pastor needs me to fill in, I just pick up the next passage. Pennington has quickly commended himself as the most helpful guide to this marvelous portion of Scripture, one of my most important life companions (along with Psalms 1, 2, 40, and 51; Rom 3; and a very few others). In Pennington one gets the feeling that one is getting a responsible round-up of scholarly opinion while also getting Kidner-quality prose and trustworthy homiletical guidance. Pennington does an exceptionally admirable job of keeping his perceived main theme of the sermon in view; this is something I don’t do so well at, and I appreciate it when others do. I occasionally wonder if that theme is as clear as he thinks it is, but he usually wins me over.
It’s pretty bold to call your work a “theological commentary” these days. Everybody wants to claim those two honorifics. But Pennington actually delivers. Here’s a flavor:
Even though the theme of the kingdom is apparent and consistent, this closing exhortation to enter according to the narrow way may seem an abrupt shift toward merely external behaviors, unlike the emphasis on the internal wholeness that Jesus has been picturing throughout the Sermon. That is, “wide” and “easy” and “broad” sound like the life of loose morals, while “narrow” and “hard” conjure images of piety and self-sacrifice and duty. Historically this text has been read and pictorially represented with images that show the broad way as impious behaviors and the narrow way as acts of service and Christian duty. Has Jesus suddenly shifted gears from wholeness/virtue to fiery-preacher behaviorism? ¶ Quite the opposite. Despite a long Christian pietistic tradition of understanding the difference between the narrow gate and broad way as a contrast between immoral behaviors and pious practices, the distinction made here depends on the same internal versus external righteousness that has marked the entirety of the Sermon. The wide and easy way that leads to destruction is precisely what Jesus has been describing all along as living with merely external righteousness, while the narrow and “difficult” way is the vision he has cast for righteousness that is more and deeper than behavior.
He ties a difficult passage back to the sermon’s theme and also relates it to all of Christian theology. And he’s done the exegetical homework necessary to get here. Highly recommended.