Summary: The preaching of the Word of God does not go out or return void, despite what we might witness or think otherwise. The Sacred Word continues to convict the heart and give new life to all who are dead in iniquity.
Fellow under-shepherd, I've been there. I know the frustration you feel when it seems that you preached your heart out this past Sunday, feeding your flock the food of the Word and proclaiming the message God placed upon you. I know what it means to study for long hours, to pray, to compose the right words, to allow the Holy Spirit to give you the right words to say once you are behind the pulpit, and to use you as a chosen vessel of service to care for the people whom God has graciously given you, whether it is in a church, mission, prison, hospital, battlefield, or other place where some angels fear to tread. You've looked out at the crowd to whom you are preaching, and it seems as if most of them are either looking at their phones, or their watch, or the bulletin, or staring into space, and some have taken the opportunity to catch a few winks before heading off to the nearest restaurant for lunch. You have given these people time, tears, preparation, and the Scriptures, yet it seems for a moment that it has all been for naught. You feel within you a mix of sadness, anger, frustration, and are tempted for a moment to walk away from it all and go do something else, which a lot of your peers have done at a rapid rate in these last days. Read on, be refreshed, reassured, challenged, and comforted in knowing that God is with you, is still on the throne, still the victor over sin, hell, death, and the grave, and is always ready and able to equip and strengthen you to fight the good fight of faith as have those before you and among you today.
If you have been faithful to Jesus Christ and the inerrancy and full sufficiency of the Bible, rest assured that what you have presented will not return without some kind of result. You have continually held out your hand to pull the drowning people into the lifeboat of salvation by the power of God, and many have taken it in gratitude and thanksgiving. Some stubbornly continued to flounder in the waves, seeing if they can stay buoyant or hold their breath long enough until things get better, only to go under into an eternal place of terror and torment where rescue of any kind is wishful thinking. Our Lord Jesus preached the Word to thousands in Judea and the surrounding areas, yet at the Day of Pentecost, He had only 120 faithful followers. This was certainly not failure on His part, but was an object lesson in showing His elect that not everyone will accept the message of the Gospel, but once they have heard it, they are without excuse before God on the Day of Judgment.
If you have been faithful and stalwart in declaring the truth of the Gospel, the results are not yours to count, but must leave in the hands of the Holy Spirit to wake the sleepers and open the ears of the indifferent, and to warm the heart of the skeptic in order for all of them to see that the Scriptures are the only reality and truth in this sin-soaked world in which we live, and the authentic source of real life and peace found in Jesus Christ alone (John 14;6; Acts 4:12, 16:31; Romans 5:6-11, 10:9-10). We also need to remember that we have not just apathetic and hostile sinners with which to contend, but also their father, the devil (Matt.13:38; John 8: 38, 44; Acts 13:10; 1 John 3:10). Satan knows he has a short time to fulfill his wicked, yet futile goals, so he will do and say anything he can to silence the message and messenger in order to drag as many souls as he can with him to the Lake of Fire (Matt.25:41; Rev. 20:10-15). He is a defeated foe, but still fights like a fanatic with nothing to lose. Our job is to get his victims to the safety of the cross and the healing arms of the Lord Jesus Christ.
The Lord Jesus called on all who would listen to Him to "repent, and believe in the Gospel" (Mark 1:14-15). By repentance, I do not mean a half-hearted mumbling of "I'm sorry" to Almighty God, hoping He will look the other way the next time we sin. Repentance according to God's standards means that He makes us look in His mirror at our reflection, darkened with wickedness and wretchedness, and it is something we do not want to face, but must in order to see that we can do absolutely NOTHING to remedy the problem in our own strength or method (Ephesians 2:8-10). Preacher, now is the time to gird up your loins, sharpen your sword, fasten your armor, and hit your people with the power of the Word and Spirit, and hit them three ways: hard, fast, and continually. Their souls are at stake, and as these days draw to a conclusion, the time to come to the cross is NOW (2 Cor.6;2).