Then Catholics should have no problem telling us what the gospel is... what was the gospel that Jesus and the apostles preached?
This was my answer to Dr. E. It is also the answer of historic Christianity. You might crack open the Church fathers once in awhile to get their perspective.
Salvation, Salvation, Salvation. He preached it and He is it. He proclaimed the Kingdom of God was at hand. He ransoms us. He redeems us. He restores us. He draws back the veil. He makes us new creatures. He died on the Cross so that we may be with Him in Glory.
He is the Truth that all truths must be measured against. He is the good news of Gods love. All things were made for Him so that the very skies can proclaim His greatness.
He is my Lord, my Savior and my King.