Joy helps against the trials of life. Hence, it is mentioned as a preparation for the rest of faith, which is prescribed in verse 6.
I. THE GRACE COMMANDED. "Rejoice."1. It is delightful. Our soul's jubilee has come when joy enters.
2. It is demonstrative. It is more than peace; it sparkles, shines, sings. Why should it not? Joy is a bird. Let it fly in the open heavens, and let its music be heard of all men.
3. It is stimulating and urges its possessor to brave deeds.
4. It is influential for good. Sinners are attracted to Jesus by the joy of saints. More flies are caught with a spoonful of honey than with a barrel of vinegar.
5. It is contagious. Others are gladdened by our rejoicing.
6. It is commanded. It is not left optional, but made imperative.
It is not an indifferent thing to rejoice, or not to rejoice; but we are commanded to rejoice, to show that we break a commandment if we rejoice not. Oh, what a comfort is this, when the Comforter himself shall command us to rejoice! God was wont to say, Repent, and not rejoice, because men rejoice too much; but God here commandeth to rejoice, as though some men did not rejoice enough: therefore you must understand to whom he speaketh. In Psalm 149:5, it is said, "Let the saints be glad? not, let the wicked be glad. And, in Isa. 40:1, he saith, "Comfort my people," not, comfort mine enemies, showing to whom this commandment of Paul is sent, "Rejoice evermore." Henry Smith
The thing whereunto he exhorteth, as ye see, is to rejoice; a thing which the sensual man can quickly lay hold on, who loves to rejoice, and to cheer himself in the days of his flesh; which yet might now seem unreasonable to the Philippians, who lived in the midst of a naughty and crooked nation, by whom they were even hated for the truth's sake which they professed. Mark, therefore, wherein the apostle would they should rejoice, namely, in the Lord; and here the sensual man, that haply would catch hold when it is said, Rejoice, by-and-by when it is added, in the Lord, will let go his hold. But they that, by reason of the billows and waves of the troublesome sea of this world, cannot brook the speech when it is said, Rejoice, are to lay sure holdfast upon it when it is added, Rejoice in the Lord; which holdfast once taken, that they might for ever keep it sure, in the third place it is added, Rejoice in the Lord alway, to note the constancy that should be in Christian joy. Henry Airay
Another note to distinguish this joy in the Lord from all other joys is the fullness and exuberancy of it, for it is more joy than if corn and wine and oil increased. Else what needed the apostle, having said, "Rejoice in the Lord always," to add, "and again I say, Rejoice"? What can be more than always, but still adding to the fullness of our joy, till our cup do overflow?
Upon working days, rejoice in the Lord who giveth thee strength to labor and feedeth thee with the labor of thy hands. On holidays, rejoice in the Lord who feasteth thee with the marrow and fatness of his house. In plenty, rejoice again and again, because the Lord giveth. In want, rejoice because the Lord taketh away, and as it pleaseth the Lord, so come things to pass. Edward Marbury
The calendar of the sinner has only a few days in the year marked as festival days; but every day of the Christian's calendar is marked by the hand of God as a day of rejoicing. Anonymous
Napoleon, when sent to Elba, adopted, in proud defiance of his fate, the motto, "Ubicunque felix." It was not true in his case, but the Christian may be truly "happy everywhere" and always.