By Entering each Shrine, one character will be allowed to donate money and get a Stat increase in return. You cannot increase a Stat past the character's racial maximum, so don't try. The Shrine of Strength is in the western part of Ambrosia. To find it, take the northernmost brushy path west from the entrance. Eventually it will narrow into a forested path heading south. Deal with the monsters in the area and continue south to find the Shrine.