The most important message for every person is that of the need for repentance - by one of the last great Puritan preachers, Thomas Boston (1676-1732).
With wonderful exposition, Boston opens up a multitude of scripture passages on an issue that it is the duty of every Christian to tell the world of - the impending judgment that awaits each one of us, the call for repentance now, and a message of hope and assurance only to be found in Christ.