1 John 4:16 tells us about the character of God: "God is love." Two verses later we find out that "perfect love casts out fear." As we focus on God's character, we realize that His plans for all of mankind are good. 1 Timothy 4:10 even tells us that "…we have fixed our hope on the living God, who is the Savior of all men, especially of believers."
Death is an enemy (1 Corinthians 15:26), while life is a gift from God. It is natural to fear death. Now all mankind are dying due to Adam's sin (1 Corinthians 15:22) – not due to our individual sins. Romans 5:12 reads, "by one man sin entered into the world, and death by sin; and so death passed upon all men."
However, during Christ's 1,000 reign, men will receive life again. Romans 8:21, "the creation (mankind) itself will also be set free from the bondage to decay into the glorious freedom of God’s children." In the resurrection, all will have their sins forgiven and learn righteousness. Jeremiah 31:34 (NIV), "No longer will they teach their neighbor, or say to one another, ‘Know the LORD,’ because they will all know me, from the least of them to the greatest,” declares the LORD. “For I will forgive their wickedness and will remember their sins no more.” At the end of the 1,000 years, people will be judged to see if they want to obey God. If they do, they will be worthy of the gift of life…forever. Only a person who chooses sin will die eternally (Ezekiel 18:4,20).
There is a group of people who are being judged now, however. These are the ones Paul calls "believers" in 1 Timothy 4:10. These have a special salvation, a heavenly calling. 1 Peter 4:17 tells us that judgment begins with the household of God. The context of verses 12-17 explains that believers who choose to live a wrong lifestyle will lose their opportunity for everlasting life. These are in danger of the second death from which there is no resurrection. If a believer finds himself to be practicing sin consistently, there is still hope. They should ask God for forgiveness through the merit of Jesus' blood. 1 John 2:1,2 say, "…if anyone does sin, we have an advocate with the Father, Jesus Christ the righteous. He is the propitiation (satisfaction) for our sins, and not for ours only but also for the sins of the whole world."