NDE's are real' and can't nobody tell me any different.
Have you ever been on a "death watch"? That is where the person is near to death, and knows it, and there is no way due to disease, etc that he can be revived? I have.
Universally there are "visions" of others, usually loved ones who have also previously surrounding the dying person. But there is also a conscience awareness of the person's ability to see both the living and the dead.
Until it happens that you are able to watch this transition process, I recommend that you lessen your degree of being so adamant. It is neither a salvational, nor a theological issue.
It surely is a possibility where demons can mimic things, but next time you have a funeral in your church, ask the pastor if he or anyone else was with the recently departed one. then ask him or anyone who was with the dying person to describe what the dead person was doing prior to death.
Make your decision on that.