Weinberg's quote is catchy but not true. There are many things that make good people do evil. Capitalism for example corrupts people. Power corrupts. There are many ways to corrupt the good.
The problem I see here is that you are talking about people who were once good people who have become corrupted to become evil people.
Would that really qualify as good people doing evil things? I don't think so. That would simply be good people becoming evil people.
Weinberg's point is that people who are doing bad things in the name of their God believe that they are still "good" people. In other words, their "intention
" is to be good. And they also believe that what they are doing is "good
Consider the following two scenarios:
Person A truly believes that God wants them to become a suicide bomber and kill "heathens". So they strap on a bomb and go to a place where they believe heathen exist, and blow themselves up killing the people they believe to be heathens.
That is a "Good Person" doing evil things while believing that they are actually doing "Good Things" for God.
So this qualifies as a "Good Person" doing "Evil Things"
But now we have a scenario more in harmony with your point:
Person B is told that if they strap on a bomb and go out and blow up a public place and kill a specific group of people their family will receive a huge amount of money and be able to take care of themselves for the rest of their lives,
Person B accepts. However, Person B knows that they are about to do an "Evil Thing" for money. So it can't be said that they are a good person doing evil things. They have become an evil person by accepting this temptation to make a lot of money for their family that will be left behind.
That's NOT a good person doing evil things. That's a person who might have previously been a good person, but who has chosen to knowingly do an evil thing. So how can it be said that they are still a "good person"?
So people who are corrupted by money or power, are NOT good people. They have chosen to become evil people.
This would not be the case for Person A who believes the entire time that they are doing the will of God.
So only religion can cause good people to do evil things just as Weinberg had suggested.
Although, mental illness can also cause good people to do evil things.
For example, in the case of Person B, they might be thinking that by killing themselves an a bunch of strangers they are still doing what best for their family and thus doing a "good thing". But we all know that such thinking is wrong. Thus for them to think like that requires that they aren't thinking clearly. So we can truly say that if they think that killing other people to make their own family rich is mentally inferior thinking. (i.e. mentally ill).
In fact, think about that.
The only other thing that is as dangerous as religion is mental illness!
I don't think that helps the argument for religion.