Romans 5:17 — For if by one man's offence death reigned by one; much more they which receive abundance of grace and of the gift of righteousness shall reign in life by one, Jesus Christ.
Receive — limited to believers, whereas death is universal
We leave our old existence, ruled by death, and enter a new existence ruled by Jesus Christ.
Paul presents a contrast in effects — the legal effect of sin is death but the effect of Jesus Christ's gift is abundant life.
We do more than participate in eternity, we live abundantly, reigning with Jesus Christ.
Death is certain. Our grace from Jesus Christ is much more so.