Remember the nine ways in which we can cause and share in the badness of others and be as bad as they are. Advising evil, commanding evil, agreeing to it, provoking evil, using flattery to get a person to do evil, concealing evil when it encourages it, actively assisting in the evil of others, by keeping silent instead of trying to talk people out of evil-doing or just walking on by when you could save a person from a criminal and by defending their evil action.
You cannot stand by and do nothing when you can save a stranger from an attacker. Then you are intending that she suffer abuse from him. You are worse than him for you will get away with it and he might kill her. You don't care about him when you let him degrade his rational nature or her either and you ruin your own dignity. We can't say we owe the woman nothing for it is nature's fault not hers that she never got the opportunity.
You shall not refuse to help others on the grounds that they never did anything for you for if they could have, they would have. Even your worst enemy would have done favours for you under the right circumstances and conditions. We all want to do good even if we don't do it. So we should be valued for that despite our wicked deeds.
To stand by and let an increase of evil happen when you could stop it makes you evil for you are assisting evil.