Our union with Christ is immortality. The one is the other. If you have one you have the other. (1 John 5:9-13) This is the gospel, the good news. The news explains that your immortality is linked to a life, a Person, not an event. There is nothing else leading to this new life or new birth of holiness but our union with that Person.
By this, our soul is quickened to a natural life, in and by Holy Spirit. God, who is immortality, declares nothing else but our eternal union with the heavenly Life and Spirit of Christ. We simply trust this is true.
But he that is joined unto the Lord is one spirit. (1 Corinthians 6:17 KJV)