What it has is Poitier as Homer Smith.
Homer is a traveling laborer — a former United States Army soldier who drives a station wagon and picks up odd jobs. He is not a heroic figure in any conventional sense. He stops at the nuns’ property because he needs water. He helps because he has skills and a decent heart and because the prioress’s absolute certainty that God has sent him is, in the logic of the film, not entirely wrong. He fixes their roof. He helps with their other practical needs. He begins to understand that they want him to build a chapel.
He does not want to build a chapel. He is not their servant. He has his own plans, his own schedule, his own life. The film is, at one level, about the comedy of a practical man being conscripted into a spiritual project by a woman whose faith is absolute and who does not recognize the distinction between a conscript and a volunteer.
But it is also about something else — about the relationship between a Black American man and a group of German women who have arrived in the American Southwest with almost nothing and need help they cannot pay for. The film does not foreground the racial dynamics, but they are present. Homer is helping people who look like the people who built the system that marginalized him. He is doing it freely, because he chooses to, because his character is generous in a specific way that Poitier renders without sentimentality.