William Burkitt on Revelation 14:12

That is, here at this time will be exercised all the faith and patience of Christ's faithful servants, and this their exercise of these graces will make it appear that they were true, and not counterfeit Christians; it follows, here are they which keep the commandments of God, and the faith of Jesus, that is, who discover themselves sincere in their profession, by obeying the commands of God, and rightly believing on our Lord Jesus Christ.

Where note, What is the characteristical mark of a sincere Christian, namely, faith and obedience united together; faith in our Lord Jesus Christ, and obedience to the will of God in all things, are never separated where they are sincere.