The word "gospel" means "good news." And for a person to fully appreciate the Good News, they need to first know the bad news.
The bad news is that we are sinners. We have broken God's commandments. We have fallen short of God's standards. There is nothing we can do to fix that. All the good works in the world will not compensate for it.
But the good news is that Jesus Christ, the Son of God, died on the cross for us and absorbed God's wrath and paid for our sin and rose again from the dead. And if we will turn from our sin and follow Him, we can be forgiven. That is the Good News, you see. That is the message we are to proclaim to the world.
This isn't happening as much as it should, however. There are some people in the church today who tell us that we must preach a holistic gospel, which is the idea that it is not just about telling people about Jesus; it is about other things. It is about doing good works for people. It is about modeling for them what it is to be a follower of Jesus. One definition of a holistic gospel says it involves living "in community to God's creation," which includes issues like pollution and deforestation.
Really? So now our message is trying to stop pollution and not cut down so many trees? No, that is not the gospel. The gospel is the message of the life, death, and resurrection of Jesus Christ from the dead. Anything short of that—or adding on to that—is a distraction. And if we fail to recognize this, we are missing the point. People need Jesus Christ, and they need to turn to Him. That is the message of the church. That is the message we are here to proclaim.