In the chapter Fire Balloons, a small group of the Church's best priests take off for Mars, to find new sins and leaving old ones behind. Mars is twice Earth's age so there is lots more sin collected they say. They plan to build a church and bring God to them. When Father Peregrine asked about the Martians beforehand, the mayor says the second race are "not quite human", round luminous globes of light and that they act intelligently. He also says they aren't human so they probably wouldn't care but then Father Peregrine says assume they have souls. At nightfall when the Martians drew near, Father Peregrine says to Father Stone don't be afraid, they are God's work.
After they leave, the echo of Father P.'s last cry causes a small avalanche. Before the rocks are about to crush them dead, they were separated and a blue light disappeared. One of them say the fire balloons lifted them and saved their lives, meaning that proves they have souls. Later on in the chapter, Father P. tries to convince Father Stone by shooting himself 3 times and all the bullets just drop to the ground along with the blue light. He says they think, judge and live with morals, they aren't animals but only another man would save him like that.
One day at the church when it is finished, the priests pray for them (globes) to come back. One of the balloons uses telepathy and the voice says a lot of things. They are the "Old ones" and legend has it that one of them discovered a way to free man's soul from the body and they lived in the winds, skies and hills forever after that. They say they will never die nor do harm and living in God's grace. Left sin behind forever and cannot reproduce, eat, make war, etc. Father P. thinks they are the "pure soul" .or in other words God himself. I think he thinks this because they are freed souls from their body, they do not believe in sin, they have the power to stop another man from killing himself, and they have pure minds, they are very intelligent.