The law was without power, because the law was made weak by our sinful selves. But God did what the law could not do. He sent his own Son to earth with the same human life that others use for sin. By sending his Son to be an offering for sin, God used a human life to destroy sin.
Christ died for all so that those who live would not continue to live for themselves. He died for them and was raised from the dead so that they would live for him.
Christ himself suffered for sins once. He was not guilty, but he suffered for those who are guilty to bring you to God. His body was killed, but he was made alive in the spirit.
For this reason the Good News was preached to those who are now dead. Even though they were judged like all people, the Good News was preached to them so they could live in the spirit as God lives.