First of all, we should try to understand the meaning of the word Gospel from the scriptures. The word gospel was derived from the Greek word Evangelion which means good news.
This kind of good news is so much different from any other good news that someone can receive. Of course, when one is blessed with a child, money, or property we usually say that they have good news. But the good news that the gospel is bearing is the good news about the finished work of Jesus Christ at the cross.
When Apostle Paul is writing his first letter to the church in Corinth, in chapter 15 he clearly defines the meaning of the gospel. First of all, he reminds them that the message that he is preaching to them was the gospel that has the power to bring salvation. And that this gospel contains the message about the death, burial, and resurrection of Jesus Christ. Therefore, we can say that the gospel is the message of Jesus Christ. (1 Corinthians 15:1-7).
The main reason for preaching the gospel is to bring salvation. That is why Apostle Paul boldly declared that he was not ashamed of the gospel of Christ for it is the power of God to salvation for everyone who believes, for the Jew first and also for the Greek. (Romans 1:16)
Someone may ask, what is the message of the gospel saving mankind from? Here is where it began. When man disobeyed God in the garden of Eden the scripture says that sin entered the world and death spread to all men. Therefore, just as through one man sin entered the world, and death through sin, and thus death spread to all men because all sinned. (Romans 5:12).
This means that everyone ever born into this world is born a sinner not because of the actions they do but because of their nature, they are born in Adam, and the scripture says that in Adam all die. For as in Adam all die, even so in Christ all shall be made alive. (1 Corinthians 15:22).
When God assessed all mankind, none was found righteous to pay for his/her sins and set themselves free from the bondage of sin, as the scripture declares that all had sinned and fallen short of the glory of God. (Romans 3:23). And the scripture clearly states that for the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord. (Romans 6:23). This means that if no ransom is paid to set man free from the bondage of sin, man would eventually perish at the end of the age.
But God motivated by His own love didn’t want man to perish but rather provided a solution to the problem of sin. But God demonstrates His own love toward us, in that while we were still sinners, Christ died for us. (Romans 5:8). The death of Jesus Christ at the cross is an outright demonstration of the love of God to all mankind. Jesus Christ while speaking to Nicodemus as recorded in the gospel of John said that for God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life. (John 3:16).