“However, you are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you. But if anyone does not have the Spirit of Christ, he does not belong to Him.”
– Romans 8:9
To be in Christ is to be in the Spirit and in the divine and mystical realm. As soon as we were saved we were put into this realm of Christ (Rom 8:9). In the way a baby enters the realm of human beings through birth, we similarly entered the realm of the Spirit through our second birth.
Adapted from Romans: The Gospel of God, by Titus Chu; Volume 1, pages 38-39