Faith and morality

I came across the following comment:

It's a classic example of a statement which sounds reasonable, but is, in fact, flawed.

Firstly, the internal logic.
This person finds the idea "disgusting" because "people do the most evil things based on faith."
The justification (the second statement) is not the only conclusion to the idea in the first statement: people also do the most amazing acts of kindness and compassion based on faith.

Secondly, the second statement itself.
The implication here is that people do evil things based on faith, therefore faith is wrong.
The truth is: people do evil things... and they will clutch at straws to find justification for it.

The very notion of 'evil' cannot exist without the prerequisite of a religion of some sort. If there is no spirituality at all, then no action can be considered 'evil', only a part of human nature.

But that's just semantics due to a bad word choice: the writer of the comment means that people do the most morally questionable things based on faith. So let's work with that.

People do evil (or morally questionable) things. That's all there is to it. The question is the justification:
Some people use faith as their justification.
Some people use their position in society as justification.
Some people use their negative experiences as a child as their justification.
Some people use their gender as justification (many women criticise men in ways they would find offensive if a man did the same to them).
Some people use their 'human rights' as justification.
Some people use the current trend of victimhood as their justification (such as SJWs being aggressive and racist towards white males).