This question was posed to me twice today by unrelated sources: What is the Gospel?
It was asked once at Bible study, and the answer was given that 'it's that Christ paid for our sins.'
In another place, it was answered similarly, but in many, many more layers (scroll down one post to see 'What is the Gospel'?), and also in the process claimed there is a Gospel of the Cross and Gospel of the Kingdom.
For what it's worth, my current answer to the question is that the Gospel is that God takes care of everything. Yes, literally, everything.