For this reason the gospel was preached also to those who are dead, that they might be judged according to men in the flesh, but live according to God in the spirit.--1 Peter 4:6
The Mormon interpretation of this verse teaches that an individual can receive his or her salvation even after they are dead. That's why living Mormons go to great lengths to ascertain the genealogy of their families. The Mormons gather in their temples to perform specific rituals on behalf of dead, non-believing relatives. This particular doctrine devised by the Latter Day Saints allows the dead relative to escape "spirit prison" and move on to one of three kingdoms in the Mormon heaven.
For there has already been enough time spent in doing what the pagans choose to do: carrying on in unrestrained behavior, evil desires, drunkenness, orgies, carousing, and lawless idolatry. So they are surprised that you don't plunge with them into the same flood of wild living--and they slander you. They will give an account to the One who stands ready to judge the living and the dead.--1 Peter 4:3-5
The context demonstrates that Peter first focused on the living, breathing evil people who were busy slandering his Jewish-Christian friends. Peter promised that these unrestrained, wild people would have an appointment with God's judgment (Hebrews 9:27). He went on to explain that those who had already died had had the truth preached to them when they were alive. So--Mormonism's doctrine of salvation for the dead that has provided millions of Mormons a false hope of salvation in the hereafter is heresy.
Earlier in his letter, Peter wrote: "[Jesus] also went and made a proclamation to the spirits in prison" (1 Peter 3:19). It is a struggle to determine exactly what's meant by this statement. Yet, it is clear that the text doesn't say that the spirits had an opportunity to accept the Christ's gospel and escape God's judgment. AND--the text clearly doesn't support the Mormon notion that someone can save a dead, unbelieving relative from sin by being baptized for that family member.
The right time to get right with God is right now!
For God says,“At just the right time, I heard you. On the day of salvation, I helped you.” Indeed, the “right time” is now. Today is the day of salvation.--2 Corinthians 6:2
Don't delay the decision to become a disciple of Jesus Christ! He is coming back. Are you ready for his return?
But you must not forget this one thing, dear friends: A day is like a thousand years to the Lord, and a thousand years is like a day. The Lord isn’t really being slow about his promise, as some people think. No, he is being patient for your sake. He does not want anyone to be destroyed, but wants everyone to repent.--2 Peter 3:8-9