To the Colossians, Paul paralleled baptism and circumcision.
Circumcision was normally administered to children eight days
after birth.
Colossians 2:11-12
In him you were also circumcised with a circumcision
 not administered by hand, by stripping off the carnal
body, with the circumcision of Christ. You were buried
with him in baptism, in which you were also raised with
him through faith in the power of God, who raised him
from the dead.
picture of Saint Paul the Apostle