Christians should be a joyous people who enjoy laughter and fellowship with each other.
Isn’t that first phrase a wonderful thing to say about other Christians? “I thank my God every time I remember you.” Paul lives a life of gratitude to God and to others. Can we say that we are thankful when we think about other people, or do we think more often about how people annoy or disappoint us?
Henry Ward Beecher: “The unthankful heart discovers no mercies; but the thankful heart will find, in every hour, some heavenly blessings.”
James called other believers brothers and sisters in His epistle. Both James and Paul loved all believers and cared for them. The frequent repetition in this Epistle of "all" with "you," marks that Paul desires to declare his love for all alike and will not recognize any divisions among them.
“with joy”--the characteristic feature in this Epistle, (also Philippians 1:18, Philippians 2:2 Philippians 2:19 Philippians 2:28 , 3:1 , Philippians 4:11, Philippians 4:4). Joy is a fruit of the Spirit. Many scholars consider this the epistle or letter of Joy. Joy gives especial animation to prayers. It marked his high opinion of them, that there was almost everything in them to give him joy, and almost nothing to give him pain. Read the book’s four chapters and notice the consistent theme of joy.
Joy is a central aspect of Jesus' ministry.