I ultimately can't, thats why you strive for consistency reinforced by replication and independent confirmation.
Then again, you're wading into a 17th century philosophy argument...not a 21st century debate involving neuroscience (of which we both know you know nothing about)
But none of that verifies your mind. Empirical evidence would cause you to deny everything since you can't judge it. Neuroscience is still subject to the same argument and we both know that. How can you ask for and judge God on the same criteria you have to subject your own mind to which you acknowledge you can't?