The gospel (aka good news):
God is the creator of all. His Son, Jesus, was a real man that came from heaven to earth to live amongst us, yet he was not acknowledged by most for who He truly was. So he was killed by those who thought He was coming out against God. God loves his creation like parents love children, but so much more. He yearns for us to love and obey Him, but He will not force us. Sin separates us from God for He is holy and cannot be in the presence of sin, and we cannot enter His holy heaven without those sins being taken away. Jesus died on earth for that purpose. He was sinless and His lifeblood paid the ultimate price for our sins, so when we believe in who He is and decide to repent of our sins and change our lives to follow Him, His blood, through our baptism, will wash our sins away forever. That is how we are added to His kingdom. His kingdom on earth. And after living faithfully as a follower, we can enter heaven with Him. That is it. The good news.
Really, that is all the early Christians knew. They didn't have the bible. Maybe some scrolls and letters distributed, but no scriptures to check out whenever they wanted. Grace covered them as they were growing and learning. Everyone is growing and learning, all the days of their lives.
The whole gospel hangs on two things: love God, and love the people He
made. Love them enough to meet their needs, and show His love through
your actions, so they will see it and want to be a part of what you
belong to. Most people do not feel anything is missing in their lives. They can't see a need for salvation and change. Change takes time---often lots of it. They probably don't truly believe in God and heaven and hell. These concepts are fairy tales to many. They can't be held to the Christian standard any more than we can be held to the standards of the world. Only by doing selfless love and THEN explaining your reason (because you are a Christian and love the people God made) will people see tangible proof of God. We, who have the Holy Spirit living inside us, are the ones who have to show the world who God is.
So Christian, let's all try to do what Jesus asks. Do good to your neighbor, to the least of these (Matthew 25), to our fellow Christians. Let's study the bible and put it into practice to the best of our ability. Get out there and be a part of society rather than isolating yourself among those like you. Try to be like Jesus. Serve your fellow man, alleviate suffering, pray often and specifically, try to avoid sinning. Love. Love. Love. Love. Love.
This is truth. This is Christianity, as I see it.