It isn't so much permanent as it is the lifetime of the body you are in (which happens to be spiritual after death, which lasts a very, very, very long time.) The kingdom (or lack of it) is within you, so the kingdom of Heaven can be within you on earth for however long you allow it in this earth body. Likewise, in the spirit whatever you have chosen will dictate where you are. Hell is a separation from God, which isn't in itself the fire and eternal damnation, but being separate from Him literally dissolves you from the inside out. It is like being burned alive forever - being separate from, and out of the protection of the Creator and Father.
We are given a relatively long time in these human bodies to make the decision as to whether or not we want to serve God. We are given obstacles, rewards, we are chastised (in terms of trials and tribulation,) we are tested for enrichment (in terms of trials and tribulation.) Through all of this we are expected to make a decision on who we want to serve. Do we want to serve devils through idolatry and self-pleasures, or do we want to serve God through patience, obedience, and self-control? It is literally your choice. And, when you make that ultimate choice, it will naturally follow you throughout your life (as a spirit.) And, since God cannot live with imperfection, you must not live with him.
With all that said, God has grace, mercy, infinite patience, lovekindness, love, and understanding for human struggle (as natural-born sinners,) and the enemies that set out to deceive and destroy us. So, it isn't a black and white "follow-me-sin-once-go-to-hell" type of thing. God works with all of us to make this battlefield called earth a fair handicap for us. For example, He sent His only begotten son to prove to God that a human can perfectly follow all of His law. Thus, God consequently has grace on us (as we were all destined to die physical and spiritual deaths as per sin, but through Christ we can have life.)
