I think misguided by the people who turn religion in to conflict and basis for hatred brings these kind of thoughts.
Throughout the history of mankind, religions played much smaller role in wars or destruction and other ideas like land, power hunger, lust, greed and hatred of fellow human being brought total annhilation of nations or made millions suffer.
Read the history of mankind. There are more weapons (and more mass destrutctive weapons) used against human beings for reasons other than religion.
And then religious people are called extremists.
We human cannot be assured of being good till some deterrants are placed. Be those the laws of land or religion and ‘preferably’ both.
This is why you said and I agree, if religion is followed properly there would be benefit to mankind.