If we choose to join Christ, and accept his offer of Life Everlasting, then we are, as they say, free indeed.
After that point we can, and sadly do, choose mortality again and again.
Said another way, it is within our power to let any specific "death" be permanent or not.
We might look at any significant loss as being too big for us to handle and thereby accept that it has killed us so to speak. A child dies to cancer, a marriage withers and dies, a dream long fought for is ripped away...how do we deal with such things?
I've taught several classes on spiritual warfare and one core premise is that all spirits, ours and the woolyboogers, are eternal. Fleshly warfare always comes down to one irreducible: whoever is dead has lost. But not so with spirits. There is no "death" in that kind of (seemingly) permanent sense. Instead, spirits suffer and they have the capacity to suffer endlessly. The spiritual response to suffering is, generally, suppression. When a spirit suffers it may go to sleep, check out. It may fold in on itself, seek solitude...and find it.
I don't mean to imply by the start of this post that the Christian has a different kind of choice than the non-Christian (or the demon for that matter). We all have the choice to check out when faced with trauma, Christian or otherwise. We all have the choice not to. In that way we all choose life or death all the time, every day. We all know people who are walking around this world but are "dead inside." Behold a spirit dead, asleep, and absent.
As we counsel those ghost-men we look for some glimmer of their heart, some ember that can be blown upon and woken up, some trace of a living human who can be encouraged to choose life once again. Spirits are eternal, and that possibility of spiritual resurrection is always available. But we do well to also recognize that the opposite is also true. It is always within our grasp to choose death and it is remarkable to look back on life, both distant and recent, and see just how often I've done exactly that.