A Continual Feast
The Bible promises a cheerful heart to the follower of Jesus Christ. Proverbs 15:15 says that "a merry heart has a continual feast," and Psalm 16:11 tells us that "in [His] presence is fullness of joy; at [His] right hand are pleasures forevermore."
Yet some believers walk around and act as though they’ve been baptized in lemon juice. They are always down about something. Yet the apostle Paul, in the worst circumstances imaginable, said, "Rejoice in the Lord always. Again I will say, rejoice!" (Philippians 4:4). He was effectively saying, "Look, if I can rejoice where I am, then you definitely can rejoice where you are."
Anyone can rejoice when things are going reasonably well. But when you are facing adversity or hardship or sickness, and you still rejoice, then you are obeying God.
Consider the words of Habakkuk 3:17–18: "Though the fig tree may not blossom, nor fruit be on the vines; though the labor of the olive may fail, and the fields yield no food; though the flock may be cut off from the fold, and there be no herd in the stalls—yet I will rejoice in the Lord, I will joy in the God of my salvation." Habakkuk didn’t say he would rejoice in his circumstances; he said he would rejoice in the Lord.
That is like saying, "Even when the car has been repossessed, there are unpaid bills piled up on the kitchen counter, and everyone in the family is sick, I’m still going to rejoice in the Lord."
God is still on the throne. God still loves us. And God has promised that He can work all things together for good to those who love Him. He has also promised that He will never leave or forsake us. So we can rejoice.