If there's a possibility that we can learn something new about an ancient civilization, then we should try to learn it. I'm not sure what there is to lose by opening this mysterious door, but I can't imagine how it could hurt. Open it and see what you find behind it.
I believe the door that scientist discovered in Egypt should be opened so we can learn more about our past. The only way to know where we are going is to understand where we have been. Considering the location is home to such religious historical significance, the door should be opened and explored.
I support the opening of the mystery door that was recently discovered in the Great Pyramid. Think of when King Tut's tomb was unearthed: that amazing find would never have been achieved if archeologists had left that particular door alone. We will never know what new thing we will learn about ancient Egyptian culture unless we open this new, mysterious door.
Some things are better left alone. We seem to have a propensity for ruining ancient historical artifacts, things that can never be regained. Leave the door closed and stop puttering around the ancient tombs of those that came before us. There is no good to be had from opening that door.