In a way, He was in the state of death through His whole life. Especially on the cross and in the grave, He faced the utter breakdown of communion with His Father, and He did all this for us. This means that we are past that stage. We have been placed into an eternal communion with God. By faith in Christ and in virtue of His atoning death on the cross, we have eternal life.
Life is communion and contact.
Only the living can see, hear, smell, touch, breathe, give and receive. Life is that which binds us to each other, to God. So when Christ says that we have eternal life, it means that we have uninterrupted communion with God and His children. Death as damnation, as breakdown of communion, is what Christ experienced and is therefore something which those who believe in Christ cannot experience. You see, also in this case the rule of atonement does fully apply.