You must know grace to preach it. No matter how great your skill or accolades, you are unlikely to lead others closer to God if your heart does not reflect the continuing work of the Savior in your life. A testimony that reinforces the message of the gospel is not merely a matter of public conduct. It is a product of consistent private meditation on the gospel that character daily requires.
Grace-focused ministers recognize the daily repentance that private prayers must include, confess to others the divine aid that grants them the strength of their resolutions, obey God in loving thankfulness for the forgiveness and future Christ supplies, model the humility appropriate for a fellow sinner, express the courage and authority of one confident of the Savior’s provision, exude the joy of salvation by faith alone, reflect the love that claims their souls, and perform their service without any claim of personal merit.
Preaching without a grace focus concentrates on means of earning divine acceptance, proofs of personal righteousness, and contrasts with those less holy. Preaching with a grace focus concentrates on responding to God’s mercy with loving thankfulness, joyful worship, humble service, and a caring witness to the Savior’s love.
The necessity of grace in balanced preaching inevitably points both preacher and parishioner to the work of Christ as the only proper center of a sermon.
~ Bryan Chapell in Christ-centered Preaching: Redeeming the Expository Sermon, pp. 39-40 (bold emphases are mine)