In 2 Corinthians 2/3 Paul considers the world-dividing impact of preaching. And faced with this he naturally asks - who is sufficient for this? As Spurgeon phrases it: "What is there difficult about preaching God's gospel?" Who can hack gospel preaching? What is the problem - something since the question is posed! Gospel preaching comes with great joy, but also with great heart-break. God does it - he spreads the aroma and brings it's effects, but does so through the weak 'jars of clay' (4v7) who he appoints as ambassadors of his gospel . Doubtless the joys are unspeakably great, and yet the very same gospel tears the world asunder, confirming death in many.
Some peddle the gospel for personal gain with their false-gospels and twisted words and they can probably handle that. But for the plain-gospel-preacher, determined to preach with sincerity, by God, before God, without letters of recommendation the sufficience must come from God.
One help is there, hearts like those of the Corinthians upon which are written letters by the Holy Spirit, letters written by the pen of the Spirit's light that shines in and writes there the same poetry and prose that accompanied the creation of the world (4v6). Hearts that like the preacher resound with the sound of the gospel, that smell to highest heaven of the sweet aroma of the gospel of the glory of God in the face of Jesus Christ.
The weight of preaching is vast and beyon man without God. And yet none of it's weightiness makes me shrink from it, I find myself drawn to it all the more.