First Earth, then Mars and its frontiers of human settlement.
Father Joseph Daniel Peregrine
An Episcopal priest who leads a mission to Mars, wishing to convert and save alien life forms.
An Episcopal priest who is second in command of the Mars mission.
Sends the priests on their mission, chooses Father Peregrine to head the mission.
Mayor of First Town
Greets the missionaries and encourages them to care for the sinners in his town.
An evolved kind of native Martian, they appear as flaming blue spheres that remind Father Peregrine of the fire balloons of his childhood.
Part of the mission to Mars, given care of the blue sphere representing a Martian Christ.
Father Peregrine, who wishes to reach out to the native Martian life forms.
The blue spheres that are an evolved form of native Martian life.
After being rescued repeatedly by the blue spheres, Father Peregrine convinces his fellow priests that the blue spheres have souls that can be saved.
The Martians speak to Father Peregrine and explain that, without bodies, they have achieved a state of transcendence removed from sin.
The main theme is the quest for spiritual redemption: Father Peregrine wishes to save the souls of native Martians, but must first determine they have the intellect to have souls and from there lead them to redemption. In this quest, Father Peregrine must wrestle with his own motivations for this, conceding that egotism may factor into his zeal. Related to this theme is the issue of faith: with their missionary work in Mars, the Fathers enter a new territory and must consider new permutations to questions of religion. Father Peregrine is excited by this prospect, and is willing to make literal leaps of faith to pursue this mission and to re-understand his commitment to God.
A related sub-theme of redemption is that of the mind / body distinction: that the mind and body can be separated in what they need and what they demand from an individual. In spiritual terms, a similar distinction is made between body and soul, soul being semantically similar to the mind in general parlance. Further, many would use this distinction as an argument that the body is inferior to the mind or soul because it has basic needs which lead to a moral or intellectual degradation. This is summed up in the aphorism, "The spirit is willing but the flesh is weak." In the story, the characters all seem to believe that sin is rooted in the flaws of the body - and that, without real bodies, the Martians are free of sin. Whether this is actually true - either practically or philosophically - is debatable, but this seems to be part of the message Bradbury is promoting in the book.
Last but by no means last is the sub-theme of awe and wonder. The fire balloons of his childhood were visions of wonder for Father Peregrine, and he experiences an even greater sense of wonder in his encounter with the Martian beings who resemble these childhood memories. As an adult, Father Peregrine is a pious man who believes his religion is a positive, invigorating experience - he speaks of God as having a sense of humor. Religion is serious, by all means, and Father Peregrine commits himself to his mission as an adult. However, he also refuses to let go of the glee and elation of spiritual transcendence, religion as a positive opening of one's view of the world. In this way, his desire to consider religion in an imaginative way rife with possibilities is in a very real sense the point of religion. By the end of the story, Father Stone shares this understanding that there is a bigger picture beyond that of human experience - which is the point of religious faith in the first place, that a higher power exists that we do not always understand but must pursue and in which we must place our trust.
On the morning he leaves on a missionary assignment to Mars, Father Peregrine dreams of the Independence Day fire balloons of his youth. Though excited by the challenge of this mission, Father wonders if going is the right thing to do; this was brought up during his conversation with Father Stone the night before on how Mars may completely change their understanding of sin. Father Stone was aghast at this happening but detected excitement in Father Peregrine over such possibilities. As they get into the rocket, Father Stone thinks of how he was chosen by the Bishop to lead this mission precisely because of his openness to new ideas and flexibility - something the Bishop believed would be more of an asset on Mars than on Earth.
Arriving at First Town, a frontier town on Mars, the mayor is happy to have priests to save the sinners of his community. The mayor mentions that there are two kinds of native Martians: one is practically extinct and the other isn't human. Father Peregrine is intrigued by the latter and finds out they are fiery spheres of blue light that are sometimes seen in the mountains. Father Peregrine decides to investigate, and Father Stone agrees to join him. Arriving in the mountains, the two priests are met by these Martians when an avalanche occurs and the humans are somehow placed safely out of harm. Father Peregrine is convinced the blue spheres saved them, which Father Stone disputes. This ability to value life further convinces Father Peregrine that these Martian fire balloons are sentient and thus have souls that can be saved; Father Stone disputes this as well. They spend the night in the mountains and the next morning Father Stone tests his faith by diving off a cliff and shooting himself repeatedly; in all cases, he is saved by the fire balloons.
The two priests return to the others in their mission and Father Peregrine offers up a way to reach the Martians spiritually: the symbol of a fiery circle replacing the familiar one of the cross, which he points out is no different from the adaptations of Christianity performed by different Earthian cultures. The mission goes to the low mountains and establish an altar to attract the Martians; some details - such as the organ and the bell - are there for the benefit of the humans, not the Martians, to help ease them into this new challenge. When ready, though not sure if it was Sunday on Mars, they played music in the hopes the Martians will arrive. They finally do so and speak to the priests: the fire balloons explain that they were once human but thousands of years ago were able to lose their bodies and took on the form of lightning and blue fire. Further, since they are without bodies, they have transcended past sin and do not require saving the way others would. The Martians go on to express their appreciation of the Fathers' efforts but again point out it was not necessary. Father Peregrine asks if he may someday return to learn from them and the Martians agree.
As they return to First Town to finally care for their human flock, Father Stone speaks of how different pieces of the Truth exist on different planets and they can only add to this sense of Truth by further exploration, as one adds pieces to a jigsaw puzzle. Father Peregrine is impressed by Father Stone's insight, and Father Stone affirms that the blue sphere they made is indeed a representation of God.
Father Peregrine's name is itself worth considering: a peregrine is a kind of falcon, a swift bird of prey that hunts by taking sudden sharp dives. This shows Father's own quest for new kinds of souls to save and the risks he's willing to take to reach them. In contrast, Father Stone's name clearly indicates a solidity and refusal to change.