Complex sentence: The group acted as a militant organization, denouncing all people who did not live the straight edge lifestyle, even those who also abstain from substance abuse, so new members were required to shave their heads, which signified a "new beginning".
Split into simpler sentences: The group acted as a militant organization, denouncing all people who don't live the straight edge lifestyle, even those who also abstain from substance abuse. New members were required to shave their heads, which signified a "new beginning".