Lesson 4: Even Inside the Church We Must Defend the Gospel

You actually can’t add to the gospel without destroying the gospel, because the gospel is all about justification by faith alone in Christ alone.
The whole gospel is that Jesus Christ died for our sins and was raised from the dead in order that whoever believes in Him will be given eternal life by God’s grace. Anything added to that detracts from and actually destroys the whole.
If you add to the basic gospel, you are reconstructing a law you already have learned you can’t keep and which can’t justify anyone.