Answer by Robert Brow
I would argue that a child raised in a home where the name of Jesus is used to mean "Oh how awful" and the f word means "bad' could not be held morally responsible for using such words till our Christian meaning was learned.
Blasphemy occurs when a person knows full well that Jesus is the Son of God and then curses or dishonours Him.
It seems to me that in the Gospels Jesus did not go around making people
morally responsible for this and that. Once they were born again into His
language for God morality would take care of itself. Two days ago we had
a couple to dinner who were converted in an Alpha course a year ago and
to their astonishment their previously foul language cleaned up overnight.