Jesus Christ is the Son of God. Christ lived a sinless life, yet died the death of a sinner - because we needed it. The truth of his death for us and his resurrection from the dead is the Gospel - the Good News of God. Paul says this in 1 Corinthians 15:1-4.
Now I would remind you, brothers, of the gospel I preached to you, which you received, in which you stand, and by which you are being saved, if you hold fast to the word I preached to you—unless you believed in vain.
For I delivered to you as of first importance what I also received: that Christ died for our sins in accordance with the Scriptures, that he was buried, that he was raised on the third day in accordance with the Scriptures.
Paul says that the simple truths of the story of Jesus are the most important truths. Jesus died for our sins, was buried and rose from the grave. Knowing these simple truths convinces us that God actually loves us and motivates us to live for Him.