There is no lack of power on Myaasia, in fact the ammount power available is too high, it is available everywhere and in huge ammounts. The lacking thing is focus. As every person wanting to do magic must be able to control and focus the power. Most are able to control only small ammounts of power. Thus power is not limited by availability but instead by the control.

The way a God gets that controlled power, is that the followers praying are actually focusing their thoughs upon their God and thus directing controlled power to the God. The God then receives this focused power and redistributes this to the followers as divine magic, causing them to not have to do all the focusing themselves, though the power to create divine magic tends to be split among the part from the cleric and the part from the God.

The way the God receives and distributes this power is the focus mentioned before. So a God needs the focus and the followers to be able to help their followers receive divine magic and to survive, as a small part of the power received is used by the God to “be God”