The fear of going to hell after death was palpable in the Middle Ages. One BBC documentary on the Crusades gave an appropriate description of this fear, stating that it felt like sin and corruption surrounded the people; the air they breathed was rank with it. They saw the frequent plagues as God’s punishment for their sins, and were willing to go to extremes for absolution. An illustration of how overwhelming the cultural fear of hell was at that time can be found in one incident described in the documentary: when Pope Urban II declared the First Crusade, he promised absolution for all those brave enough to take up the Cross, and entire settlements joined the crusade and left for Jerusalem.
Of course, not everyone was willing to go on a crusade, but it was commonly believed that sacrificing one’s time, money and energy to visit the holy places and artifact reliquaries dotting the Medieval landscape was a worthwhile gesture, demonstrating that pilgrims seek to be closer to the Almighty and to atone for their sins.
A D&D game may not have the same cultural fear of hell as Medieval Europe, but a fantasy RPG landscape can be dotted with shrines and destinations of spiritual significance that can add flavor to a D&D campaign. At a dungeon master’s discretion, some sites may be under the control of monsters or rival religions, leading to a series of adventures to recapture them.