The gospel is just about justification, getting saved, or evangelism.
The majority of the writers on the subject (Piper, Keller, Chapell, etc.) have been quite clear in their objections to this point. The whole purpose of their writings on the topic is to assert that the Gospel is to be central not only in justification but also in sanctification. As defined by these and other writers, the Gospel is that doctrine that teaches that we are unable to merit God’s favor due to sin, that we must come to God simply through faith in His Son, and that God, through Christ, gives us everything we need for life and godliness. This objection is flawed because it fails to understand the source material on the topic.
For a further explanation see my pastor’s brief introduction to the topic here.