See when you pray you”re doing some psychological work. That psychological work has some physical effect. Therefore the physical effect that you are subjected to must be attributable to psychological work in past. Therefore your birth is subjected to your psychological work in past. Therefore there must be past lives.
I was pointing to the fact that work of mind (which I termed as psychological work) has a physical effect of curing some disease. That is our mind works and we see its physical implication. It is true that GOD is beyond psychology. Still he is so kind that he notes our psychological work and rewards accordingly. Prayer is one example. Therefore if we take this as cause and effect (cause: prayer and effect: cure), then physical event of birth (effect) must have some work of mind in past (cause). Secondly this theory also explains why there is so much diversity in living conditions of living beings. One is rich, another suffers from starvation. One is very happy another is full of grief. This theory also asserts all virtues like kindness, compassion associated with God are justified and what one gets is what is due to him or her. You think something and God will reward you positively or negatively according to what you think. Thus when you pray, God notes that you”re trying to approach him and according to intensity and sincerity of prayer he rewards you, protecting your interests all the time.