Good point, and yes he is testing us, not only our intelligence but everything, in fact this is the meaning of life, it's to win or to loose the test, our intelligence is superior to other creatures, and it gives us the possibility to choose, so we should've be responsible of our path and accept the penalty.
"(...) Christians irredeemably strayed from the teachings of Moses and Jesus."
That assumption is wrong since 'irredeemably strayed' is assuming, they are all not believers. And Quran says that even Christians and Jews will go to paradise. 2:62
Indeed, those who believed and those who were Jews or Christians or
Sabeans - those who believed in Allah and ...