The secret of Christian joy—is the peace of Christ in the heart. Then one is not dependent on circumstances or conditions. Paul said he had learned in whatever state he was, therein to be content. That is, he had formed the habit of happiness and had mastered the lesson so well, that in no state or condition, whatever its discomforts were, was he discontented. We well know, that his circumstances were not always congenial or easy. But he sang songs in his prison with just as cheerful a heart and voice as when he was enjoying the hospitality of some loving friend. His mood was always one of cheer, not only when things went well—but when things went adversely. He was just as songful on his hard days—as on his comfortable days.
Then Paul gives us the secret of his abiding gladness, in the word he uses—”content.” It means self-sufficed. He was self sufficed—that is, he carried in his own heart the springs of his own happiness. When he found himself in any place, he was not dependent on the resources of the place for his comfort. The circumstance might be most uncongenial. There might be hardship, suffering, poverty; but in himself he had the peace of Christ, and this sustained him so that he was content.
There is no other unfailing secret of happiness. Too many people are dependent upon external conditions—the house they live in, the people they are with, their food, their companions, the weather, their state of health, the comforts or discomforts of their circumstances. But if we carry with us such resources that things outside us cannot make us unhappy, however uncongenial they may be—then we have learned Paul’s secret of contentment, which is the Christian’s true secret of a happy life.(By J. R. Miller, 1898)