St. Francis of Assisi, painted by Giotto
From early on, Christians believed that some holy people,
when they died, not only went to heaven but had the special attention
of Jesus, and had special powers themselves,
so that they could cure sicknesses
and answer prayers of all kinds. These people were called saints. Both
men and women, and often children, became saints.
It was hard to tell, of course, whether someone was going to become a saint after he died, and sometimes people disagreed about it. But generally you looked for this kind of signs: a saint would lead a very holy kind of life, and often would not marry or have children. He or she would never do anything bad. A saint would do miracles even while he or she was alive, like curing sick people or saving a city from being destroyed. And often, a saint would die some kind of special death, either being killed by bad people or being taken up to Heaven alive or something like that. After the saint died, too, the saint's bones and clothes would continue to perform miracles.
Some important Christian saints (for example) were Saint Peter, Saint Paul, Saint Michael, Saint John the Baptist, and Saint Anne (Jesus' grandmother). Joan of Arc, who was burned for a witch, was made into a saint after her death.
This idea that some people had special connections to the gods goes back a long time before Christianity, to West Asian ideas about holy men and women. There are also similar ideas in Chinese and Indian Buddhism, for instance - check out the story of the boddhisatva Cheng-Huang.