This is one of the first Wildcards available in the game, and maybe the most important one, at least for players that intend to Found a Religion. It will give you +2 Great Prophet Points per turn, even without a Holy Site; or if you dutifully construct it and its first building (the Shrine) - 4 GPPs total, plus any eventual bonuses. Although this may not be enough to earn the first couple of Great Prophets (considering how ridiculously buffed the AI is in the beginning of the game on higher difficulties), it will ensure you get one soon afterwards.