At this moment, Jesus was totally part if the human race--connected with everyone who had ever lived and would ever live--so he was dying every death that every human being had died or would ever die (Hebrews 2:9) Because He rose again in His true Body, we now have the potential to be part of His family. (Hebrews 2:10-11) It is however, an option--we are free to reject it. When we accept it, we also accept the Holy Spirit, the part of the Godhead which is the connecting link.
At the Community Easter Sunrise Service, Rev Joshua Beckley pointed out that St Paul didn't say "sins" but "Sin". In this context, it is talking about attitude: about rejecting belief in Jesus, in who He is and what He did. No matter how many good things we do, and how many bad things we do not do, God can't see them if He has not been a part of them. If we do believe, He can deal with "sins" if we let Him. As long as we are in this body, we have both the ability to connect with God, and our humanity. When the human body dies, the connection with humanity is lost, and if we have rejected the spiritual connection with God, He no longer can see us. That is a tough one to grasp! But if you don't know the Host, how can you expect a ticket for the banquet?
It's a little bit like an electrical circuit. As long is it plugged into the grid, it can power all sorts of interesting things. If it loses the main connection, it cannot be restored from the grid; it has to be reconnected from the user end. If we turn off the switch from our end, He won't override it; and when it is unplugged, the connection is lost. The grid can't even "see" it.
The other side of this coin is that if we are connected with God, He separates us from our sins forever! I was reminded of a Gospel chorus:
Down in the depths of the deepest sea.
Lie all the sins that belonged to me.
Buried for time and eternity,
Down in the deepest sea!
(Norman J Clayton, 1946)