The Spirit is God's Yes....and Joy!
Paul and John agree essentially on yet another point. John calls the Spirit “Paraclete”, that is, advocate, helper, defender, comforter. He is thus the adversary of the diabolos, the “prosecutor”, the slanderer, “who accuses our brethren day and night before our God” (Rev 12:10). The Spirit is the Yes, just as Christ is the Yes. Correspondingly, Paul emphasizes joy very strongly. We may say that the Spirit is the Spirit of joy and of the Gospel. One of the basic rules for the discernment of spirits could be formulated as follows: Where joylessness rules and humor dies, we may be certain that the Holy Spirit, the Spirit of Jesus Christ, is not present. Furthermore, joy is a sign of grace. One who is serene from the bottom of his heart, one who has suffered without losing joy, is not far from the God of the Gospel, from the Spirit of God, who is the Spirit of eternal joy.
Ratzinger, J. (2008). The God of Jesus Christ: Meditations on the Triune God. (Brian McNeil, Trans.) (p. 113). San Francisco: Ignatius Press.