From Tony Reinke.
Ten notes about gospel faithfulness, a collection derived from Galatians 1:6-10:
1. Gospel faithfulness is required of the entire church, not merely its pastoral leaders.
2. No matter how religious we claim to be, no matter how close to the truth we reside, no matter how recent our conversion, sinners are all prone to an unintentional replacement of the gospel with a counterfeit.
3. According to Paul, we can relax our grip on the biblical gospel suddenly and dreadfully easily (ταχέως).
4. To add anything to the gospel is to desert the gospel.
5. To add anything to the gospel is to have a “no-gospel.”
6. To modify the gospel is an act of defection from God.
7. The content of the gospel is unchanging and “embodies a core of fixed tradition which is normative so that no preaching deviating can be called ‘gospel’” (Fung).
8. No authority—not even an angel from heaven—has the right to modify the gospel because “the authority of the gospel resides primarily in the message itself and only secondarily in the messenger” (Fung).
9. A divine curse (ἀνάθεμα) is threatened against teachers who—in claiming to preach the gospel—have deviated from its biblical, Apostolically-defined, substance.
10. Faithfulness to the genuine gospel requires that our hearts be freed from the chains of man-pleasing, in order that we might serve Christ. We cannot serve Christ with an adjusted gospel.
Already Not Yet 
Amen! this was a helpful reminder to my heart.