George Washington wrote in his Farewell Address that one cannot have morality without religion.
You don't need a god to make you ethical,
But the "wrong" god can make you unethical.
Throughout history, people have killed other because their "god" justified it.
We have ISIS killing those who don't believe as they do, and we had Torquemada of the Spanish inquisition torturing and killing those who would not believe as he did.