There is a direct link between rejoicing and knowing. This is what led Jesus to say, “I have said these things to you so that my joy may be in you, and that your joy may be complete” (John 15:11 NRSV). Notice the direct link between what is spoken and what results–an indwelling and complete joy.
So what did Jesus say? First, there is the relationship between Jesus the true vine and the branches in him (John 15:1-8). Second, we see the theme of “abide in,” holding all these verses together: when we as branches abide in Jesus, the true vine, he abides in us, so that we are able to bear much fruit and thus glorify the Father (vv. 4, 8).
Third, we also discover that as the Jesus, true vine, has loved us with the same love with his Father, the vinedresser, has loved him. Fourth, Jesus has commanded us to abide in his love (v. 9). But to abide in his love, we must keep his commandments, just as he kept his Father’s commandments and abide in the Father’s love (v. 10). So we have discovered another link–the link between loving and doing. If we love Jesus, we will do what he says.
Jesus said that all this is to our joy–a joy that comes from him and a joy that will only be complete in the knowing.
Therefore the more we abound in our knowing intimately the Triune God is the more we will abound in our rejoicing in the Triune God.