On 28 October 2014, Mez delivered the biennial MacMillan Lecture on Evangelism at Edinburgh Theological Seminary, talking about evangelism, the spiritual situation in the housing schemes of Scotland, and how we are going to close the gap between the church and the poorest in our society.

“You can go into almost any city centre in Scotland, and you can take your pick of churches. Christianity might be shrinking, but largely there’s still a bit of a pick-and-mix for people to choose from. You cannot do that in the poorest parts of Scotland today, they do not have the same choice as the more affluent areas. And if this trend keeps going as it’s going, that evangelical Christianity in our country hardens and solidifies within a more educated, middle-class cultural enclave, what we’re going to find is the distance growing greater and greater between large swathes of our country that come from less privileged backgrounds. . . . This would be contentious if not for the fact that this is basically what Thomas Chalmers said to a group of middle-class ministers and theological faculty in the 1800s . . . that was his point then. . . . Thomas Chalmers would be absolutely incandescent to see, prophetically, just how true those words have become . . . if it’s not too bold, he’d probably be on the board of 20schemes.”