The 'Good News' is only good if we buy the 'Bad News'
I use this analogy. A salesman comes to your town and tells you that everyone in this town has a terrible, awful disease which no one knew about until this salesman shows up. Although the salesman can offer no proof of this disease he swears we will all suffer and die from it. However, he says the "good news" is he has the cure, and one can only get the cure from him, but he will save you and you will be eternally grateful to him if you but buy his product. Meaning: Christians tell us that we all have sin and that sin will bring us a terrible awful fate. Nevermind that until they came along, no one ever suspected we had this terrible condition and the Christians can't offer one shred of proof that we have 'sin' or that a terrible fate awaits us. But, the 'good news' aka Gospel is they have the only cure and we can only get it from them - one can only be saved from sin and hell through Christ, not by living a good life or practicing peaceful Buddhism, etc.