If evangelicals know anything today about Chalmers, it’s probably his sermon, “The Expulsive Power of a New Affection.” Few may know he was arguably the most famous British preacher at the time, a brilliant mathematician who theorized on everything from astronomy to politics to economics to social reform, and an evangelical who longed to see Christ proclaimed in slums of Scotland and far away nations.

What is remarkable is how he wielded his immense intellect to serve the church. Consider the following encouragement and warning about preaching:

By far the most effective ingredient of good preaching is the personal piety of the preacher himself . . . How little must the presence of God be felt in that place, where the high functions of the pulpit are degraded into a stipulated exchange of entertainment, on the one side, and of admiration, on the other! and surely it were a sight to make angels weep when a weak and vapouring mortal, surrounded by his fellow sinners, and hastening to the grave and the judgment along with them, find it a dearer object to his bosom to regale his hearers by the exhibition of himself, than to do, in plain earnest, the work of his Master.

Put simply: in your preaching, are you exalting yourself or the Savior?