Christians ever tought of this?

It is very clear that the God in the O.T. is very cruel and dictative but rather kind in the N.T. How come the same God change so dramatically. After all, He is God, so He should not be changing His character. This the most sensible reason to me. In the old days it was ok for people to condemn gays and treat women as inferior, which led leaders(priests) to portray God as such to strike fear and discipline to the society. In the modern society killing, sacrificing, slavery, , etc. is not acceptable anymore, which forced the novelists who made up the stories in the Bible to portray God more fitting to the modern society. The Bible and Christianity did not just pop out the dust, it came for a reason. The reason is that dictatorship through a feared religion benefited high authority both financially and economically. It makes me wonder why modern people still obeys a religion that once slaughtered and tortored humanity. Is the faith you have really for this religion?