Every doer of sin is considered a slave of sin (John 8:34). Since sin brings about our death, we are considered dead in our trespasses (Romans 5:12; Ephesians 2:1). Now, yes, the scripture does mention us as being once dead from our trespasses. However, take note that the first resurrection is not said to occur until after Satan has been bound, which is after the great tribulation (Revelation 20:4; 11:1-11). But before the thousand year reign. So, no one can be considered truly alive until later, then. Since, all of the signs of these events have not occurred yet (compare Revelation 6:15-17). Matthew 24:13 shows that no one is truly saved until the end. And 1 Thessalonians 4:16, 17 shows that all those going to heaven will be resurrected together. So, they will all be made alive at that time. As for those who are to remain on Earth, and Matthew 24:13 still applies, they are to be considered resurrected after the thousand year reign (Revelation 20:5; Psalms 37:29). At that time, the judgement will occur and death will be brought to nothing (Revelation 20:11-15; 1 Corinthians 15:20-28). Everyone who remains, will be alive forever and the rest will cease to exist (Revelation 21:3, 4; Psalms 37:10).