Why is being united with Christ essential for eternal life?

Union with Christ is central to the Christian faith and the essence of eternal life, as it signifies a profound and transformative relationship between the believer and Jesus. In 1 John 5:11-12, it states, 'And this is the testimony: that God has given us eternal life, and this life is in His Son. He who has the Son has life; he who does not have the Son of God does not have life.' This passage asserts that eternal life is only found in Christ, illustrating that to have Him is to have life itself.

The theological implications of this union are rich and manifold. This union is not based on mere association but on deep personal covenantal relationship wherein believers are made one with Christ in His death and resurrection (Romans 6:5). Through this unity, they receive life-giving grace, the righteousness of Christ, and the assurance of their place in the family of God. As stated, 'He that eateth me shall live by me' (John 6:57), indicating that continual dependence on Christ sustains spiritual life. Thus, the importance of being united with Christ is highlighted as the foundation of both our present spiritual vitality and our future eternal existence.