abovementioned verse forbids asking questions whose controversy can never be settled, and there will always remain a chance to argue, whatever stand you may take.
Jews and Xtian scholars tried hard to trap muslims in such useless discourse, like one trying to ascertain the number of people of kahaf('cave'), pagans had their own varying number, so quite tactically they probed muslims, unknowingly some muslims also pondered on such questions, who were forbade to do so.
Islam asks believers to observe things and ponder over the system God has created, rather than pursuing purposeless inquisite.
This clarification nullifies your second assumption too. Afterall Quran doesnt ask to kill xtians, non muslims or anybody. becoz it is from ALLAH. and ALLAH never gives an order to do Injustice.
I praise ALLAH that he gave me enlightment to believe Him. If beleiving ALLAH means puppet of Quran, which I disagree, I am proud of it.
