4 Rejoice in the Lord always. I will say it again: rejoice! 5 Let your gentleness be evident to all. The Lord is near. 6 Do not be anxious about anything, but in every situation, by prayer and petition, with thanksgiving, present your requests to God. 7 And the peace of God, which transcends all understanding, will guard your hearts and your minds in Christ Jesus.
A second element, essential to ‘standing firm in the Lord’ is rejoicing. Not only to rejoice but always to rejoice. Now Paul is probably in prison and the Philippians are probably suffering persecution and Paul is talking about joy. He must be nuts! Or he's walking the talk.
Paul is not talking about a case of the Monty Pythonesque ‘always look on the bright side of life’. Nor is he referring to a joy so deep it doesn't show on your face! He tells the Philippians to rejoice in the Lord. ‘In the Lord.’ To stand firm in the Lord we must rejoice in the Lord.
To rejoice in the Lord is to rejoice in who he is, what he has done. To stand firm is to get things into perspective; not to look at our circumstances but to who he is and what he has done. Our circumstances do not go away, they do note change but they are certainly made to look less problematic if we know God.
There are several phrases Paul adds to his ‘Rejoice in the Lord’ statement. Firstly, letting there ‘gentleness’ or ‘steadfastness’ be evident in their lives, will help them rejoice. Secondly, that God is near. This could be an eschatological nearness—Jesus will return soon—or that God is near to help. The second for me is more likely. Thirdly, they SHOULD NOT be anxious about anything but they SHOULD, talk to God about what they need. Finally, and this is the result, the Peace of God, will guard their hearts and minds in Christ Jesus.
The important thing to note here is the place of THE LORD. Rejoicing, therefore, is always ‘rejoicing in THE LORD’, THE LORD is near, make known your requests TO GOD, and it is the peace of GOD that keeps you in CHRIST JESUS.
How is this rejoicing cultivated that we may stand firm?—the closeness and presence of God. We must know God’s presence close to us to know his joy and his peace. Your relationship with God must always be a strong priority. Without that the turbulent seas of life will knock us off balance and make us fall. This is done via what used to be called the "spiritual disciplines" of Bible reading, prayer, confession, adoration, service. Do not give up on your quiet times with God. If you do you will not stand firm.