Thus goes the well-known Christian chorus, quoting John 15:11,12,
"This is my commandment
that you love one another,
that your joy may be full."
Great song, but a tremendous simplification of Jesus' message in John 15, which is an amazing call to enter into the thought and actions and will of God, just as Jesus had experienced with God the Father.
The phrase "that your joy may be full" occurs several other times in the New Testament (John 16:24, 1 John 1:4, and 2 John 1:12). Lets look a little more closely at 1 John 1:4 in context. While it says that this scripture was written that our joy may be full, the context indicates that a specific message was being imparted to provide joy to its hearers. Both the message preceding and following this text have implications for happiness.
The verses prior to 1 John 1:4 tell us that Jesus revealed to us the Father, and that Christian fellowship is in fact to participate in the connectedness that Jesus and the Father share. This resonates with the message in John 15, our first instance of the "joy may be full" phrase. The verse after 1 John 1:4 specifically states what this message of happiness is. It is that Jesus revealed to us that God the Father is good. All good. Not Yin and Yang. Not predominantly good. All good.
"This then is the message which we have heard of him, and declare unto you, that God is light, and in him is no darkness at all."
How is that simple bumper-sticker message, "God is Good", the basis of complete human joy? Surely there is more to living a joyous life than perceiving God's character? Perhaps God's gift of marriage helps us understand this truth? True joy in marriage is not in things, money or circumstances, but in knowing beyond a shadow of a doubt that one's life partner is a good person.
Lets ponder the linkage, if any, between an understanding of God's goodness and complete human joy.