The joy that Jesus Christ brought to the world is different than temporal happiness for a few main reasons.
First, the joy of the Lord is supernatural in origin. I wrote on Wednesday how temporal happiness can rise and fall depending on our circumstances. It is purely natural in origin, and it can be destroyed by things that are natural in origin.
The joy of the Lord on the other hand is given to us by God, and because of that, it cannot be taken away from us. We might not always recognize it, and we might forget about it at times, but it is always there for us to tap into as Christians.
Second, the joy of the Lord is pretty confusing for people who are not Christians. If our temporal happiness is tied to our situation, then Christians like us are going to seem pretty strange when we have this joy during difficult times. For people who are relying on temporal happiness, difficult times are going to only bring sadness.
Relying on the joy of the Lord is something different. Christians still can become sad, so this is not to say that Christians are always going to be happy. That would be demonstrably false. After all, even Jesus wept at the death of Lazarus even though He fully understood He was going to bring Lazarus back to life. Therefore, joy is not equivalent to temporal happiness.
Rather, it seems to be something more substantial as I said on Wednesday.
I think that part of the answer comes from John 16. Jesus is preparing His disciples for His imminent crucifixion, and He tells them the following:
"Very truly I tell you, you will weep and mourn while the world rejoices. You will grieve, but your grief will turn to joy. A woman giving birth to a child has pain because her time has come; but when her baby is born she forgets the anguish because of her joy that a child is born into the world. So with you: Now is your time of grief, but I will see you again and you will rejoice, and no one will take away your joy. In that day you will no longer ask me anything. Very truly I tell you, my Father will give you whatever you ask in my name. Until now you have not asked for anything in my name. Ask and you will receive, and your joy will be complete" (John 16:20-24, NIV).
The joy that is going to come to the disciples is salvation through Jesus Christ. That is something that will not be able to be taken away from the disciples. We see that also in Hebrews 12:2 where we read about Jesus:
"For the joy set before him he endured the cross, scorning its shame, and sat down at the right hand of the throne of God" (Hebrews 12:2, NIV).
It seems as if the moment that ultimately brought joy was the crucifixion. When Jesus paid the penalty for all of our sin for all time, He was also looking forward to great joy. Our joy seems to be tied to our salvation, that great hope of all who follow Jesus Christ.
It makes sense because what can be greater than knowing that we are going to spend eternity with Jesus Christ? No matter how great anything might be on earth, it will not even compare to the joy that is coming our way. This promise is what gives Christians this joy; it is not based on our circumstances.
I think that’s what we need to consider then when we talk about joy. We cannot confuse it with happiness because it is rather obvious that Christians are not happy 100% of the time.
It is something more substantial and significant that is a direct result of the sacrifice that Jesus Christ made for us, and we can only have that joy through a supernatural source. When we think about what it means when we sing Joy to the World, we need to go a little bit deeper than just talking about happiness.