1 Peter 4:6
For for this cause was the gospel preached also to them that are dead, that they might be judged according to men in the flesh, but live according to God in the spirit. For for this cause was the gospel preached also to them that are dead, that they might be judged according to men in the flesh, but live according to God in the spirit.
The gospel was preached to people who are now dead so that, though judged by human standards in their bodily life, they might live according to God in the spirit. It was preached so that those condemned as humans in the body might live God's life by the Spirit. In its setting this belongs to Peter's teaching about turning from sinful desires to do God's will. It calls for no longer living the rest of life to human lusts but to God's will.
This is made possible through God's gift of His Son living as a child and a man, suffering rejection and crucifixion. Through His sinless life and atoning death, humanity can grasp divinity, stop sinning, escape the corruption in the world through lust, and share the divine nature.
Because the end of all things is near, gaining eternal life by overcoming through the blood of the Lamb and the word of testimony requires accepting the sacrifice made and entering covenant by sacrifice. It requires overcoming temptation daily and being sober and watchful in prayer. It requires holding fervent love that covers many sins, showing hospitality without grudging, and using every gift to serve others as faithful stewards of God's grace.