The glory of preaching is that God accomplishes his will through it, but we are always humbled and occasionally comforted by the knowledge that he works beyond our human limitations. Ours is only the second sermon; the first and last are those of the Holy Spirit, who first gave his Word and quickens it in the hearts of hearers.
These truths challenge all preachers to approach their task with a deep sense of dependence on the Spirit of God. Public ministry true to God’s purposes requires devoted private prayer. We should not expect our words to acquaint others with the power of the Spirit if we have not met with him. Faithful preachers plead for God to work as well as for their own accuracy, integrity, and skill in proclaiming his Word.
Success in the pulpit can be the force that leads a preacher from prayerful dependence on the Spirit. Congregational accolades for pulpit excellence may tempt one to put too much confidence in personal gifts, acquired skills, or a particular method of preaching. Succumbing to such a temptation is evidenced not so much by a change in belief as by a change in practice. Neglect of prayer signals serious deficiencies in a ministry even if other signs of success have not diminished. We must always remember that popular acclaim is not necessarily the same as spiritual effectiveness.
The spiritual dimensions of preaching undercut much of what you may be tempted to believe about this book—that if you learn to speak well enough, you can be a great preacher. Not true! Do not let the necessary emphases of this book, the comments of others, or the desires of your own heart mislead you. Great gifts do not necessarily make for great preaching. The technical excellence of a message may rest on your skills, but the spiritual efficacy of your message resides with God.
~ Bryan Chapell in Christ-centered Preaching: Redeeming the Expository Sermon, pg. 33 (bold emphasis mine)