Converting to Judaism was always an option for those who God killed. For the Jews in WW2, this was not the case.
Now, God has the right to create and take life, as he sees fit. He warns people and give them a chance (sometimes many chances), and if they don't comply, he destroys them.
If there was a rough neighborhood and you warn people several times that the laws of the city were going to be roughly enforced unless they comply, and still they don't, it is your duty and within your power as (whatever position you hold, mayor, etc) to enforce the law.
It works sort of like that, however were comparing God with a Mayor.
Nothing to see here, move along.