Lateral thinking

[Cynical Ninja]

You ask either twin
"What door would the other twin tell "me" to go through"
Then do the opposite

If you ask the twin that always tells the truth - he would honestly tell you the door the evil twin would say goes to heaven.. and so you do the opposite


If you ask the Evil twin - he would lie directing you to the door to hell - again you do the opposite.

You are along the right lines but you have added a completely unnecessary level of complication to it.

The actual answer is even simpler than your version, in the answer you don't even have to do the opposite of what you are told. In the answer the guard basically tells you what door he's guarding, its that simple.