You take one senetence from a whole chapter and use it to judge Christians? The message from the chapter is for Christians to withstand the judgement of the unsaved. It is an encouragement. He points out the rewards of God’s gospel so that persecuted Christians would realize God’s judgement is for them.
Those that “obey not the gospel of God” or unbelievers. The gospel is the good news. The first law is to love the Lord your God and have no other Gods before him. The gospel is that of God’s grace through Jesus. It is a call of love. It is that which makes us perfect, not our own perfection.