Indeed; I'm familiar with this. If you believe in the Christian God, it's possible to rationally assert that no test can prove Him, but that after death everyone will know that He exists.

The simulation argument, linked to recently here, I believe, has much the same features without the religious baggage: there is no experiment you can do which will provide direct evidence that you are, or are not, in a simulation. In the extreme case, the simulators could just stop the sim, back up, and change the outcome of the experiment (or just your perception of the outcome), and continue on.

However, it might still be important to your future survival whether you act as though you are or are not in one, in either case.