It is not difficult for our flesh to rejoice in that which benefits it. Our children, after opening their birthday present or Christmas gift, will respond with words and actions that reveal their joy. But when there are aches and pains in our bodies, the joy is gone; and often we are inclined to groan and weep.
A serious question therefore is whether we rejoice and respond with singing when we hear of and experience the salvation which our covenant God has given us through His Son. In fact, the question is whether we rejoice in that gift of His Son, and of the salvation He realized for us.
The question, however, is not merely, or in the first place, whether we rejoice because we have been set free from the awful punishment which we deserve. The question is whether we rejoice because we have been set free from the love of sin wherewith we were born.
In Philippians 3:1 Paul writes, "Finally, my brethren, rejoice in the Lord. To write the same things to you, to me indeed is not grievous, but for you it is safe." Here he gives us the reason for true joy and everlasting thankfulness for a most precious gift from our God. That gift is His Son Who makes it possible for us to walk in deeds which reveal that Christ is our Lord. It means that we rejoice because He made us able to serve Him and thereby to say that He is our Lord. It means that we are glad that we can live the way He did when He was here on this earth, that is, that we can serve God with all our heart and soul and mind and strength.
Yes, we need to be exhorted to rejoice in Him as our Lord. For we still have our old sinful nature; and we will have it until the day that we die and leave this life. Therefore Paul wrote and told us to rejoice in the Lord. In fact, it is God Who here calls us to rejoice in Christ as our Lord. This He does through the apostle.
Let not simply your lips say it. Let your deeds say it. Walking in sin declares that you do not want Him as your Lord. Walking in love to God is saying that you rejoice that Christ and not Satan is your Lord.
Read: Philippians 3
Psalm 73:26 "Moreover, we believe and teach that the Son of God, our Lord Jesus Christ, was from all eternity predestinated and foreordained of the Father to be the Saviour of the world. And we believe that he was begotten, not only then, when he took flesh of the Virgin Mary, nor yet a little before the foundations of the world were laid; but before all eternity, and that of the Father after an unspeakable manner." Second Helvetic Confession "The pleasures of being forgiven are as superior to the pleasures of an unforgiven man as heaven is higher than hell." R. M. M'Cheyne