Throughout history people have followed and served the gods.
There are those who are fanatical and those who only slightly believe.
There are also those whose faith allows them to perform wondrous acts or even miracles.
These individuals are called Divine Mages, Priests or Clerics. These individuals can make water safe to drink, heal wounds and even cure diseases or blindness.
They have the ability to find and disperse the undead as well. They can do all these things because of the faith and servitude to their deity.