This simple verse is a direct command, with the word repeated for double emphasis: “Rejoice … rejoice”.  Seeing the world through a Biblical lens we know that God's goodness and celebrating with joy is not a Christian option, nor is it to be reserved for special occasions.  It is to be the everyday normality of living in Christ (1 Peter 1:6).  Yet that is not every believer's experience, either for themselves or of others - which is why we need to be instructed to rejoice.

Looking at their circumstances, many might reply, ‘But I don't feel full of joy, so I cannot rejoice’.   That is precisely the problem.  Our feelings change according to what consumes us.  If we take our eyes off Jesus there is little cause for joy in a sinful world.  But when we are absorbed by the love of God, the grace of Christ and the fellowship of the Spirit, joy floods our emotional horizon (2 Corinthians 13:14).  For those who need more help, Paul says, “Rejoice always, pray continually, give thanks in all circumstances; for this is God’s will for you in Christ Jesus.” (1 Thessalonians 5:16-18).  And in Ephesians 5:20 Paul says we should give thanks “for everything” – the good and the bad so that our joy may be in the Lord, rather than our emotional reaction to events in our life.

We do not know why Paul wrote this.  Perhaps it was an antidote to interpersonal friction (Philippians 4:1-2), or to the inevitability of suffering (Philippians 1:29).  Naturally, in any adverse circumstance Satan tries to induce fear and despondency: but in Christ we can see that God is always working everything together for our good (Romans 8:28). Jesus certainly suffered, but He looked with joy beyond the suffering to the Divine purpose (Hebrews 12:1-2).  Therefore, He is a great example to us to endure and not give way to fear, nor give up (Hebrews 12:3).  Paul's double instruction to rejoice is more than a helpful reminder that we can have inner peace because God is in control.  We must celebrate that peace as a reminder to ourselves of God's covenant faithfulness, and as an expression of delight that we are blessed with every spiritual blessing in Christ (Ephesians 1:3).  Rejoicing in the Lord is an essential act of worship.

Rejoicing is not dependant on temperament or culture, circumstances or feelings, but on obedience.  It is true that happiness depends on what happens, but joy is the result of the Holy Spirit's work in obedient hearts (Galatians 5:22).   F B Meyer, who ministered on both sides of the Atlantic a century ago identified the relationship between peace and joy – ‘Joy is peace dancing. Peace is joy at rest’.  Rejoicing – that is the outward celebration of inner peace - is an act of worshipful obedience which marks the believer as belonging to Christ, especially when the outlook is bleak.  Your colleagues at work cannot fail to notice, and then you will need to give gospel answers to their questions (1 Peter 3:15).