There is a sin committed by many Bible-believing Christians, a sin that borders on the curse of Revelation 22:19, taking away from the words of the Bible. More specifically, it is a common sin of the enemy: Redefining the words of Scripture.
What word? Joy.
A well-meaning Christian says, "Oh, joy is not happiness, it's deeper. It's contentment, optimism, hope." No! It is not! Hope is hope, and joy is joy. If in doubt, look at the first definition that pops up in my "joy def" search online:
"Intense and especially ecstatic or exultant happiness, or an instance of such feeling"
(https://www.wordnik.com/words/joy accessed 2024-03-08).
When well-meaning Christians say joy is not happiness, they are denying what God says repeatedly, that we should have "exultant happiness" in the Lord. Why would anyone really deny that God should make us happy? How can such grievous foolishness occur?
The "problem" comes from our rich English language. We happen to have a lot more words than NT Greek. "Happy" comes from Middle English, "joy" from Latin via French. They are synonyms.
"But I rely on the Bible not the dictionary," someone says. Okay, get this: the New Testament has only one word for both joy and happiness, 'chara.' To say they are different sucks the meaning from the word. In the Bible, joy and happiness are the same emotion because they are the same word.
Here is proof. Matt. 13:44 says a man was filled with joy ('chara') when he found a treasure in a field. So the emotion one might have winning the lottery is the same emotion the Bible says we should have in God! Is it deeper? Of course. God is eternal. Our life in heaven is eternal.
As a consequence, Php 4:4 is very correctly translated, "Be happy in the Lord always. Again I say, be happy!"
So, why do well-meaning Christians say what they say? They lose sight of the OBJECT of joy. Pushed to say more, people will admit, "Well, happiness comes from circumstances, joy comes from God." Yes! That's the difference, not our English synonyms. What Christians should be saying is, "Same feeling, different cause. Be happy in the Lord!"