What is the gospel?

The gospel is the good news of Jesus Christ, the eternal Son of God, lived a sinless life, died for our sins, and resurrected from the dead. Jesus' birth, life, death, and resurrection reconciles all who would trust in him to God and promises that all things will be made new. He is inviting all of humanity to receive this good news through repentance and faith.

...But God, being rich in mercy, because of the great love with which he loved us, even when we were dead in our trespasses, made us alive together with Christ—by grace you have been saved— and raised us up with him and seated us with him in the heavenly places in Christ Jesus...

-Ephesians 2:4-6 (ESV)