Jesus suffered the punishment for our sins, so there is no reason why we should suffer for them too. The price for sin has already been paid by the only one who could fully pay it and that is Jesus. All Jesus asks of us to make His redemption ours, is faith in Him as our Lord.
Sin has a wage it must pay and no one can avoid payday without faith in Jesus. Anyone who does not receive the new birth will be held liable for all the wrong they committed as a result of their sinful nature. Those who receive the new birth through faith in Jesus, don't have a sin nature and will not receive the payment of death.
Physical death as well as every result of the sin nature (i.e. sickness, depression, fear, etc.) is only a by-product of the spiritual death that was already inside of us. The Lord told Adam that in the day he ate of the forbidden tree, he would surely die (Genesis 2:17). Adam didn't die physically that day but he did die spiritually. Physical death came 930 years later for Adam (Genesis 5:5) as a by-product of his spiritual death.
Eternal life is a gift. The dictionary defines a gift as "something that is bestowed voluntarily and without compensation; a present." We have nothing to do with earning this gift. All we have to do is receive it by faith.