It seems to me that there are three ways you can preach the gospel defectively and as a result not see much if any lasting fruit:
1) The First and Most Catastrophic form of defective preaching is preaching that is completely devoid of biblical substance: No Law, No Gospel. This is what Michael Horton has described as “Christless Christianity” or what a pollster has nicknamed “moral and therapeutic deism.” In this form of preaching, the pastor stands up and tells stories, he makes people laugh, he makes them weep a little as well, he makes them feel good, he encourages, he entertains, he gives tips, he tells them they are OK, and that god loves them just the way they are. In other words, he or she does the Christian version of motivational speaking. Maybe he does it well, or maybe he does it poorly, but regardless, it puts people to sleep about their true state, and no reformation ever results from it. Jeremiah tells us this was the most popular form of preaching in Judah: “From the prophet even to the priest Everyone deals falsely. For they have healed the hurt of the daughter of My people slightly, Saying, ‘Peace, peace!’ When there is no peace” (Jer. 6:13). Unfortunately, surveys tell us that this is the most popular form of preaching in America today.
2) The Second form of defective preaching is preaching that has LAW but no gospel: This is preaching that aims to convict men of their sins. It tells them what the law of God says and it tells them how they have FAILED to do what the law says. It tells them they are rebels and that they deserve Hell. But then it says, “so DO BETTER! Stop committing those sins and keep the law! Live a moral and godly life!” And what happens is that people hear it, and many are convicted and they do try to put away some of their bigger sins and start living a better life, and so they try to stop sinning for little while but find that they keep falling back into sin again and again. This method of preaching will never produce any real fruit because there has been no real change in the sinners heart – there is no new life, no grace, and they are still under the dominion of their sins. Spurgeon described the situation this way:
“A sinner without grace attempting to reform himself is like Sisyphus rolling the stone up hill, which always comes down with greater force. A man without grace attempting to save himself, is engaged in as hopeless a task as the daughters of Danaus, when they attempted to fill a vast vessel with bottomless buckets. He has a bow without a string, a sword without a blade, a gun without powder. He needs strength. I grant you, he may produce a hollow reformation; he may earth up the volcano, and sow flowers around its crater; but when it once begins to stir again, it shall move the earth away, and the hot lava shall roll over all the fair flowers which he had planted, and devastate both his works and his righteousness. : he cannot deliver himself from his sins.”
This kind of preaching prevailed during the time of Charles Finney in the 19th century. With his blazing eyes Finney transfixed his hearers and called them out as sinners, sometimes by name even, and told them that they had the power to stop being sinners and live lives pleasing to God. But when they tried to follow his instructions, they failed miserably, and the areas that experienced this kind of preaching became especially hardened to the gospel. By God’s grace, this kind of preaching has grown very rare and we shouldn’t mourn it’s passing.
3) The Third form of defective preaching is preaching that has Gospel, but no law: Men are told to flee to Jesus, but why they need to flee is never made entirely clear. The gospel seed is sown, but the hearts of the hearers are still hard and stony. In this form of preaching, Jesus meek and mild is set before us. We are told how wonderful a Savior He is. We are told that He died for the sins of all men and that He loves us and is waiting for us to ask Him to come into our hearts. We are told that if we will pray the prayer, or walk the aisle, or raise the hand, we will be saved. We are asked “don’t we want to do that?” Sometimes we are even told that not accepting this offer of salvation might involve “choosing to be separated from God” (whatever that means.) But it is presented to us as though it were an offer of something good given to people who might appreciate it, and the majority of people who hear the offer are in no sense convinced that they have need of this Jesus fellow, especially if they don’t particularly like church, or hymns, or being told over and over again to bow their heads and close their eyes and raise their hands. They are still what Christ called stony ground hearers. And although they might make an initial commitment, they seldom stick to it (Mark 4:16-17).
This form of preaching has done terrible damage to the modern evangelical church, because it has filled churches with attenders in whom there is no repentance and no true conversion. These unconverted “converts” have little or no interest in things like biblical teaching, prayer, and the sacraments so in order to keep them coming back on Sunday we have to entertain them with a host of gimmicks, and in order to explain why they don’t grow in grace and holiness (the real reason being that they have no root and are actually as dead as when they first entered the church) we have to change the theology of the bible to create a category called “the carnal Christian” who is supposedly a Christian who has accepted Jesus as His Savior but not his Lord. They say they are Christians but they live just like pagans. In other words, he or she said “I do”, but then kept on faithlessly playing the harlot with their idols without turning or returning.
So what do we need? We need true preaching, preaching that has both law and gospel. Preaching that like the Apostle’s preaching sets the true situation before men, it tells them that they are sinners, that they have been breaking God’s commandments from their childhood and that the wages of sin is death and that the reason their lives are so messed up is that they have been disobedient to God. This preaching warns them that they are in grave danger not of “separation from God” but of spending eternity in Hell which is a place of eternal punishment where, to quote Jesus, “their worm does not die and the fire is not quenched” (Mark 9:43-48). It warns them that if they are not Saved that God is in fact ANGRY with them (Psalm 7:11). This is preaching that tells the unconverted that they are sinners in the hands of an Angry GOD as Jonathan Edwards famously put it. It warns them that young and old, rich and poor, male and female, unless they repent and believe in the Lord Jesus Christ and flee to Him, and trust in Him for salvation that they will be eternally damned. We need preaching that emphasizes the need for total trust in and commitment to Christ.
It is this preaching that plows up the stony soil of the heart through the convicting work of the Holy Spirit, and without that happening the Gospel seed can no more penetrate the sinners hardened heart than a seed can penetrate a solid rock.