So here is my take at a simple, concise, yet not too short, definition of the Gospel.
God, through the life, death and resurrection of Jesus, is reconciling all things and renewing all things. He has made Jesus Lord and calls us to trust, follow and obey Him by faith through the power of the Holy Spirit.
What do you think? To long? To short? Something missing?
Ok, your turn. How would you describe the Gospel?
(Jesus is Lord is a good answer when you only have 3 words. I'm letting you have more than that!)