What does the term 'mystical union' mean in Christianity?

'Mystical union' describes the deep, spiritual bond established between Christ and believers, distinguished from mere intellectual recognition. This union encompasses both subjective experiences, felt and known by individual believers, and objective realities, rooted in God’s eternal election. The concept implies that believers are not only united with Christ in terms of faith but are inherently part of His body—the Church. Ephesians 1:4-5 affirms this truth that believers are chosen in Christ before the foundation of the world, highlighting the depth of this relationship. It signifies a life-giving relationship where Christ dwells within believers, empowering them to live according to His will.