A mother wrapped her newborn baby in towels and, with his umbilical cord still attached, left him nestled in a Nativity scene inside a New York church this week.
The baby was found by the church's custodian after he returned to the empty chapel after lunch on Tuesday.
CCTV footage showed the mother entering the church with her newborn bundle and leaving without him.
"[The custodian] heard some crying, a baby crying, and he looked all around," Brooklyn Bishop Octavio Cisneros told CNN affiliate WPIX-TV.
Emergency services were alerted and took the baby to hospital where he is reported to be in good health.
The parish priest, Rev Christopher Ryan Heanue, said the story carried a message of hope.
He told the New York Times: "The story went most certainly viral, because it's a beautiful story. I pray that it's a story that will make people appreciate the gifts of life."
The mother has been found and will not face charges. New York's safe haven law allows newborns to be left anonymously at a church but they must be either left with someone or the authorities must be alerted.
Bishop Octavio Cisneros said the baby boy was a "miracle child".
- nzherald.co.nz