Gospel
The word gospel derives from the Old English gōd-spell (rarely godspel), meaning "good news" or "glad tidings". The word comes from the Greek euangelion, or "good news". The gospel was considered the "good news" of the coming Kingdom of Messiah, and of redemption through the life and death of Jesus, the central Christian message.
(Etimology from Wikipedia)
Gospel as music genre tells story about the good news.
In the Bible, John 3:16 says "For God loved the world so much that he gave his one and only Son, so that everyone who believes in him will not perish but have eternal life."
It's a good news that no matter how messed up our life, God's ready to have a relationship with us. It's totally not because of our perfection, but solely because of His perfect love towards imperfect us. It's possible because His Son, Jesus Christ, has redeemed us. It's indeed a good news!
* Left : "Amazing grace", a blues jam session/live music show at Sultan Jazz, December 2013, with James Flynn, Ywenna Carolin and Prakash Xavier.
* Below: "As a deer panteth", trying an acoustic guitar at Heirlooms music, October 2014