The Gospel means "Good News." The greatest news of all is that we can have peace with God, our Creator, because of the life offered to us through the work of Jesus Christ. It's our only hope.
Those who believe and place their trust in Jesus Christ are commonly called Christians. The term "Christian" can be a confusing one, though. It's thrown around so commonly in our culture that it hardly describes anything of solidity anymore. If Jesus Christ is the namesake of a Christ-ian, we must look to Him to find out what it means. The place to go for that is in the Bible.
In short, a Christian is a disciple (or follower) of Jesus who has been saved from their sin and ultimate separation from God for eternity by the death and resurrection of Jesus Christ. This is confirmed and assured through their faith in Jesus as their Savior, and evidenced through the regeneration of the Holy Spirit--who transforms them into the likeness of Christ through His power.
In the Bible, God lays out simple truths to us to reveal the nature and work of Jesus as part of God's unstoppable plan:
Life is not made up of "good people" and "bad people". We are all in the same boat. - Romans 3:23
Even though we are all sinners deserving of Hell (separation from God and all that is good), God loves us enough to do something about our insurmountable problem. - Romans 5:8
He didn't act because we are deserving of it or because we have earned it. God provides salvation through Jesus because He has mercy on us. - Titus 3:5
It's God's grace that allows you to come to Him - not your efforts to "clean up your life" or work your way to Heaven. Morality doesn't save--Jesus does. - Ephesians 2:8-9
Your sin earns you death. Jesus took the payment you were owed on Himself. That penalty for sin must be paid. - Romans 6:23
To admit we are sinners means turning away from our sin and selfishness and turning to follow Jesus. The Bible word for this is "repentance" - to change our thinking about how grievous sin is, so our thinking is in line with God's.
All that's left for you to do is to accept the gift that Jesus is holding out for you right now. - Romans 10:9-10
If you have placed your faith in Jesus and His work alone, and understand Jesus has bought you (redeemed you) and is now your master--if you're ready to follow Him as His disciple and submit your life to Him, the Bible says that you are a disciple, or in other words, a Christian.
If you have made this decision, confess it! Start by telling someone you know is also a Christian, and then commit yourself to building the Church, which is Jesus' work.