A system that punishes the innocent is evil. Period. Unfortunately there are times when the religious institutions try justify thought crime and they need to be resisted too. "Sin" for example, is not a sword for any of us to use against others and yet we do every day. This is also because all sin is considered equal, even though reality says otherwise.

There is a clear difference between sin and evil. Sin is meant to teach. Meant to grow you as a person. Meant to help us experience good times and bad so we can appreciate the different feelings. Where it starts to become evil is when your actions begin to harm others. When you start violating the consent of others, that is when you are on the dark path. The slippery slope is NOT what we "allow" people to do or don't do. We don't have any authority to decide what's best for people in the privacy of their lives. That is the mindset of tyrants/insecure children. What the slippery slope actually is, is allowing others to harm others and doing nothing to stop it.

Consent is the moral absolute that transcends all ideology and is irrefutable as being the chief moral standard.