After we die, we cannot go to heaven without great merit. With more merit, we can become heavenly beings. Only those with the greatest merit can become Bodhisattva. The case of becoming Buddha is very, very rare, so now we won't talk about it. Those who haven't earned much merit, nor committed big crime won't go to hell or become lonely ghosts wandering around after they die, but they will become low-level astral beings, and live in the astral realm which is the closest place to our earth. Heavens are a little bit higher.
Some souls are more sensitive. We can say soul or master; they are the same. Sometimes the soul can go out from our body and then other beings might borrow our body and live there for a while. They may want to use this body to do something, something bad probably, or to enjoy various situations in this world. When the body is borrowed by many beings, we say that person is "possessed". We can hear many different voices coming from him, not his voice alone. Sometimes he even doesn't want to talk, but cannot control his mouth to make various sounds. That's because at that time many astral beings have come and borrowed his body. They talk nonsense or do illogical things, which he himself cannot control.
Astral realm is also beautiful. When we entered it, we may think that we are really in heaven, or in the ultimate place of Nirvana. We cannot tell whether it's true or false. Their world is one hundred times more beautiful than ours. The women there are also very, very beautiful. Therefore, no matter if we go there through our own spiritual practice or are taken there by those astral beings, we will get lost without a real good Master or a good guide. Seeing the beautiful scenes there, we would think it's really awesome and extremely great. If we believe them at that moment, they will take us up there after we die.
Many people call themselves spiritual practitioners, but few become Buddha, because they don't understand the law of this universe and are cheated by astral beings. That being would say, "I'm such and such Buddha coming to teach you. You are already a Buddha now. No need to worry about such trivial things. You shouldn't be attached to anything in spiritual practice, etc." He would talk like this so that we would think we are something, and we are already in such a high level that there's no need to mind the law of the universe. It will be terrible if we really think so. Therefore, without wisdom, spiritual practitioners are easily cheated and cannot escape afterwards. Since that kind of Maya's obstruction has great power, we cannot leave as we wish. He would drag us back. He would not only forbid us to leave, but also place a big rock in front of us.