Speak to RuneScape gold dad uhrney and he'll inform you you have to pay for the key. (If you accidentally burn off the key, there'll be a respawn at a chest at the east corner of this room.) "use" the unholy leather onto the unholy key, then use the unholy covered key on the molten lock. This will free father uhrney, who will then extinguish the flame using a prayer. Talk to dad uhrney and he will inform you that they captured him to get a particular package that he had for the priest in lumbridge, and he'll also tell him that he delivered the package to his great friend wizard mizgog in the wizard tower once he heard that his captors were coming for him.
He will give you his promised 2k plusd another 30 for ship fares. Return to port sarim, and make your way over into the wizard tower. Talk to magician mizgog and he will tell you father uhrney said you're coming. He'll provide you"wrapped Package. Duplicates price 7.5k. Bring the package safely to the priest, who will be waiting for you in the church. He'll then ask you that god you encourage; Guthix, Saradomin, or Zamorak.
However, if you say yes, then he'll tell you to move into town and get black wolf robes (top and bottom, found in clothing stores) a green cape (guthix), cape of winners (blue cape, winners guild) or red cape (Zamorak, clothes store) and a staff of air(Saradomin) water (guthix) or fire (Zamorak), that may be seen in Zaff's Staff store.
He will return them and you will get (by way of example, Saradomin) Saradomin priest gown top and bottom, Saradomin priest cape, along with saradomin priest staff. He will also give you a prayer book of your god. (The priest robes and team along with cape will change appearance to match.)
Prayers from prayerbooks take the place of a spellbook or the default spells. These prayers aren't actually prayers, and do not take away prayer points, but do not give magic or prayer xp when throw. All these"prayers" are like the lumbridge home port, in that they have recharge times. Each god has a different cheap RS gold prayer book.