How does the marriage analogy explain that we are one with Christ?
The marriage analogy shows that just as a husband and wife become one, so the believer and Christ become one. Therefore, if anyone is in Christ, he is a new man. This oneness is not repairing the old nature but a new creation, energized by God's power.
Les explains that the marriage analogy illustrates oneness: as husband and wife become one, so the believer and Christ are one, and therefore if any man be in Christ, he is a new man. He stresses you cannot just fix up the old. Using the dead-battery illustration, Les says Adam's sin made his soul a sin nature and his spirit died, losing fellowship with the Creator. Cleaning a dead battery does nothing; it needs outside energy. Likewise, we were dead from Adam's sin and need God's outside power to energize our spirit. When He energizes the Spirit, He makes us a new person, or a new creation.