Answer:
Pope Urban II promised the people that if they participated in the Crusades ALL of their sins would be washed away.
Step-by-step explanation:
To encourage Christians to participate in the Crusades he told the people that if they went to reclaim their Holy Land from the Muslims their sins would be washed away and in their afterlife they would be well-awarded. This highly encouraged knights, but also the peasants the promise of immunity since sin was prevalent in Europe.