Grace basically means an undeserved act of kindness. This is one of the most enduring actions of love that could ever be conceived.
The Gospel simply put is "The Good News" of what Christ has done for you and me. This is the message and meaning of who and what Jesus is and has done.
It means from the Greek, "A Good Message" literally or more to the point "Good News" referring to a message of good tidings such as...
This was the rallying cry of the Reformation. The main point that caused Luther and Calvin to challenge the Catholic Church and it's teachings.