Since you cannot understand or see anything outside of our universe then how would you explain you assertions that a god does exist that you can neither see nor understand?
Are you still continuing with this silly argument? What do you mean by "outside" our universe when outside deals with space? Just because God has "access" to an infinite number of dimensions He wishes to create, does not mean he cannot reveal himself to us in our known dimensions.
Your statement itself holds three assertions:
1) God is unable to "enter" the dimensions he created for us,
2) We cannot know ANYTHING about God if we cannot know EVERYTHING about God, and
3) God has never in the past and will never reveal himself to anyone. None of these you can prove.