>> I suppose my main question is whether my support of legalization would negatively impact me within the Church of Satan should i choose to join. <<

Providing you refrain from stating any usage of the drug until the day comes that it is no longer illegal, I doubt there would be a problem.

We do not oppose the right to work to change laws in accordance with our own viewpoints or the right to disagree with state imposed laws. That is what a democratic country is. We only oppose illegal activity in itself.
Human beings are as significant as a cigarette burn in the sun.