Something wonderful about the life and teaching of Jesus is that they are all about joy.
An angel tells Mary of her pregnancy with these words: "I bring you good tidings of great joy, which shall be to all people" (Luke 2:10).
And even before Jesus was born, the wise men "when they saw the star, they rejoiced with exceeding great joy" (Matt 2:10). Even an unborn baby (John the Baptist) leapt for joy after the news was announced (Luke 1:44)!
Then when John the Baptist later meets the mature Christ Jesus, he says "this joy of mine is fulfilled. He must increase, but I must decrease. He who comes from above is above all" (John 3:29-31).
The topic of joy pops up again and again in Jesus' parables. For joy, Jesus instructs that we should sacrifice all for the kingdom of heaven: "The kingdom of heaven is like treasure hidden in a field, which a man found and hid; and for joy over it he goes and sells all that he has and buys that field" (Matt 13:44).
Jesus promises the faithful will enter a state of eternal joy: "Well done, thou good and faithful servant: thou hast been faithful over a few things, I will make thee ruler over many things: enter thou into the joy of thy lord" (Matt 25:21).
Jesus defined his earthly mission when he said, "now I come to You [God], and these things I speak in the world, that they may have my joy fulfilled in themselves. I have given them Your Word." (John 17:13).
Christ Jesus said that joy is the result of following his Commandments: "If you keep my commands, you will remain in my love, just as I have kept my Father's commands and remain in his love. I have told you this so that my joy may be in you and that your joy may be complete" (John 15:10-11).
Jesus disciples came home with joy when they found that his teaching heals: "The seventy returned with joy, saying, 'Lord, even the demons are subject to us in Your name'" (Luke 10:17).
Jesus said that their will be joy in heaven when one sinner changes his attitude: "I say to you that likewise there will be more joy in heaven over one sinner who repents than over ninety-nine just persons who need no repentance" (Luke 15:7).
Jesus tenderly promised his followers that "your sorrow shall be turned into joy (John 16:20).
Before Jesus was crucified, he told his followers and friends: "I will see you again and your heart will rejoice, and your joy no one will take from you" (John 16:22) and "until now you have asked nothing in My name. Ask, and you will receive, that your joy may be full" (John 16:24).
And finally, when the disciples first encountered the risen Christ Jesus their reaction was "joy" (Luke 24:41) "and they worshipped him, and returned to Jerusalem with great joy" (Luke 24:52).
"For we are Christ’s, and Christ is Thine, O Father: His joy remains in us through endless days." -Christian Science Hymnal 356:3