God doesn't require us to scientifically prove his existence. God says he has already given us the evidence of himself and even his invisible attributes, in ourselves and in his creation, so that anyone who denies the truth about him is without excuse.
God may not require us to do so, but we're entitled to do so under the Free Will clause, right? Or is Luke 4:12 an injunction against 'testing' God in that sense rather than in the moral temptation sense?
If we're testing whether God exists, then we're hardly going to consider what God allegedly said as being relevant given that accepting that God said anything at all is necessarily already predicated on believing that God exists.
Rather, if we wanted to establish God's existence according to the principles we use to validate other claims, then we'd need to be able to point to actual independent corroborating evidence. It is very difficult to imagine what form that evidence would take, but that's really a problem for the claimant.
What's worst of all about your statement there is that there's an implication that if anyone finds the God claim lacking, they have no excuse. This isn't true at all. A proponent of ANY position owns the burden of proof - if believers in gods cannot satisfactorily provide convincing reason or persuasive evidence, then the fault is theirs and their justification for belief is shown lacking.
Let's put it another way: would you find your own statement above convincing if it was written by a Hindu about Siva? If a Hindu said this to you, would it cause you to then simply believe that Siva exists? Or would you hold the Hindu's claims to a higher expectation than you're asking others to hold yours?