17 "When I saw him, I fell at his feet as though dead. Then he placed his right hand on me and said: “Do not be afraid. I am the First and the Last. 18 I am the Living One; I was dead, and now look, I am alive for ever and ever! And I hold the keys of death and Hades."
One can only imagine the feeling John must have had at this point being confronted with all this overwhelming sound and imagery, but Christ is quick to comfort him and tell him not to be afraid.
When Jesus says that he 'holds the keys of death and Hades' in His hands, he means that he can literally save all of us human beings who are trapped in the urges and behaviors dictated to us by our bodies and our human experiences from going to hell after death. The actions of Christ and God and the others in the Heavenly realms are pure, but in this plane of existence our bodies and our emotions urge us to behaviors that are inherently selfish and pleasure-seeking, which lead us into actions that stain our souls. Those actions are what we call sin, and the damage to our spiritual material, our souls, is real.
Christ offers us a way to avoid ending up in hell, by repenting to Him of our sins and asking His forgiveness. Forgiveness by Christ is an actual physical act though it happens in a realm that human beings cannot yet detect or measure by physical means. Christ removes all the scar material from past sins out of our soul, and redeems us in purity that He and God possess. Then, when we ask Him into our hearts to be our Savior, and accept Salvation, He comes into our spirit and begins to help us to let go of impure behaviors one after the other, a process which takes the rest of our lives. This is the 'marriage' part of Salvation, whereas the initial repentance and His initial forgiveness are the 'wedding' part.
We still must continue to draw closer to Him by turning away from these sinful behaviors as we are made aware of them, and we still must continue to repent and ask forgiveness of our sins when we become aware we have gone astray. This is a lifelong relationship of growing in closeness to the image of Christ and His teachings, which are best laid out in the Sermon on the Mount in the Gospel of Matthew.
If you want to accept Salvation from Christ here are some resources:
A Prayer for Salvation from Christ:
Lord
Jesus, I confess my sins and ask for your forgiveness. Please come into
my heart as my Lord and Savior. Take complete control of my life and
help me to walk in Your footsteps daily by the power of the Holy Spirit.
Thank you Lord for saving me and for answering my prayer.
A more detailed step by step process:
https://www.wikihow.com/Accept-Jesus-Into-Your-Life