If Rome taught anything close to the Scriptural definition of the gospel of Christ, there would be no argument. Its pagan traditions disqualify it. Sorry.
The Baltimore Catechism: Part One: The Creed, The Unity and Trinity of God
The Baltimore Catechism: Part One: The Creed, God and His Perfections
The Baltimore Catechism: Part One: The Creed, The Purpose of Man's Existence