The good news of the Gospel is that God's righteous Son, the Lord Jesus Christ, paid for all of our sins when He died on the cross, so that if we believe in Him, who also rose from the dead, we can live in Heaven with Him for all of eternity. That is the good news. But unless one first understands the bad news, this good news will not have much significance.
The bad news is that we have all sinned; we have all disobeyed God's law and thus deserve death. This means we deserve to spend eternity in the lake of fire, separated from God forever. That is the bad news -- our sin and its wages. And until people recognize their plight, why would they repent of their sin? But once they realize that their destiny is Hell, the lake of fire, then they may see their need and accept Christ as Saviour.
Why are people reluctant to spread the Gospel? It likely boils down to not wanting to offend others. Telling someone that they are a sinner and thus destined for eternal death in the lake of fire can be quite insulting, and as most of us would rather not offend others, we leave them on their path leading to destruction. Although we fail often, we must strive to never be reluctant or ashamed to tell about our Lord and His power to save.
One of our main purposes ought to be showing the teachings of the Bible, God's inspired Word, to unbelievers, in order that they might understand the Gospel and be saved from what they rightly deserve. Not telling them these things may be less uncomfortable for us now, but after they die they will find out -- when it is too late. We must remember that this is a message we are commanded to preach; it is a message of the utmost importance, and is what one's eternal destiny depends on. It ought to be in love and with accordance to the Lord's commands that we speak to others about their destiny without Him, and what He did for them.
For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek. (Romans 1:16)
Someone who has been thoroughly persuaded into thinking that this life is it, and that there is nothing afterwards, should be reminded that this is only a jot of time, and that their existence will be eternal. We ought to be trying to bring others to Christ in light of eternity, not this life.
But if our gospel be hid, it is hid to them that are lost: In whom the god of this world hath blinded the minds of them which believe not, lest the light of the glorious gospel of Christ, who is the image of God, should shine unto them. (2 Corinthians 4:3,4)
And he said unto them, Go ye into all the world, and preach the gospel to every creature. (Mark 16:15)
There are those who preach the Gospel, giving people promises such as if they accept Christ, they will receive peace, joy, and everlasting happiness in this life. Their efforts in the Gospel may be commended, but I cannot endorse their method. Such things may be true, but professing believers are likely to quickly fall away when things in life disappoint them. The Apostle Paul wrote: "If in this life only we have hope in Christ, we are of all men most miserable." (1 Corinthians 15:19) Thankfully we have hope in Christ both now and for all of eternity.
Perhaps a useful illustration is that of a man flying in an airplane, who during the flight is handed a parachute by a stewardess, and told to put it on, as it will make the flight more enjoyable. He tries it on, and wears it for several minutes, but finding it quite uncomfortable, takes it off in disgust. Contrary to what the stewardess had said, rather than make the flight more enjoyable, the parachute had made it less enjoyable. Now suppose that same man is handed a parachute by a stewardess, and told to put it on, as there is a fire in a fuel tank on the left wing. He then quickly puts it on, and does not even notice it being uncomfortable, as he prepares for the jump.
See the difference? The reason for the parachute in the first scenario is entirely different from the reason in the second scenario. It is similar with the Gospel. If promises are made about this life, people will quickly fall away. However, if we show them the eternal consequence of rejecting the Gospel, those who accept Christ are not likely to fall away. Now while it is unlikely that anyone handed a parachute in the second scenario would reject it, many still choose to reject the Gospel, even though what is offered is much greater than the parachute, which can merely postpone death for perhaps a few more years.
Why do people choose to reject the Gospel? It could be they believe there is no God. Or perhaps they do not believe the Bible to be God's Word. Or it could even be because they feel they will have to change their ways if they receive Christ. Regardless of their reason, they will soon wish they had listened.
While great care should be taken to assure that there are not any un-Biblical doctrines or inconsistencies being presented in the message, the manner in which the Gospel is preached is important and should also be considered. Salvation is simple, and we should not make it confusing with hard to understand words in our speech. Often the best Gospel preachers are those who say the least, and those who are very able at defending every doctrine are not necessarily gifted at keeping things simple when preaching. Even young children should be able to understand. The Scriptures give us numerous examples of both Jesus and the apostles preaching, and we would do well to pattern our own after such.
Sometimes raised is the issue of how often the gospel should be preached. Now while this might be debated, particularly when it is preached among those who know it well, neglecting it altogether would certainly be unfortunate. One advantage of having a regular, simple preaching of the Gospel is that it gives ample opportunity to often attending children (and adults) who are not saved to learn about salvation. Another advantage is that those in the church can bring unsaved acquaintances to such meetings knowing that the Gospel will be presented - and that it will not be an appeal for donations.
For Christ sent me not to baptize, but to preach the gospel: not with wisdom of words, lest the cross of Christ should be made of none effect. (1 Corinthians 1:17)
Obviously we would prefer that the Gospel be preached to those who have never heard it. But in much of North America, comparatively few will come to meetings presenting the Gospel, as there is little interest in spiritual things. However, even if we may be unable to muster much of a crowd, the possibility of the salvation of even one soul from eternal damnation would make any effort worthwhile, although it does not necessarily make Gospel meetings a particularly effective means of reaching people.
Finally, we should remember that the Gospel is effectively spread in other ways; with quite likely the most valuable being personal one-on-one witnessing and teaching, hopefully letting our Christian life and conduct shine for others around to see and desire, that they too might receive eternal life.
Let your light so shine before men, that they may see your good works, and glorify your Father which is in heaven.(Matthew 5:16)