Why is having Christ in us essential for spiritual life?

The doctrine of Christ in us is critical in understanding what it means to have true spiritual life. Colossians 1:27 illuminates this point, stating that 'Christ in you is the hope of glory.' Without Christ indwelling us, our flesh is devoid of any good. Our ability to live righteously and bear fruit stems entirely from our union with Christ, as articulated in John 15:5, which states that apart from Him, we can do nothing. This dependency portrays the vital nature of faith—the act of partaking of Christ by faith is how we receive life and sustenance. He is our righteousness, our provision, and our lifeline, and through this relationship, we are preserved and empowered to live for His glory.