How do we know that the joy of Christ is fulfilled in us?

Christ's joy is fulfilled in us when we have faith in Him and experience the blessings of our union with Him. John 17:13 reveals that Jesus desires His joy to be made complete in us, which is realized through our fellowship with the Father and the Son. This joy is a fruit of the Spirit and can be fully experienced in our lives when we trust in the accomplishments of Christ, which lead to peace and assurance. Therefore, true joy is not just an emotion but a profound spiritual reality stemming from our relationship with Jesus.