Joy
Michael Heiser clip
Joy is being theistically optimistic.
Pulpit Commentary on Philippians 4:5
There is no joy in a narrow selfishness; joy involves an open heart, a generous love. Joy in the Lord tends to make men gentle and mild to others.
Paul would have the heathen say, “See how these Christians love one another.” Their mutual love would be the blessed means of drawing fresh converts to the faith.