The nuns never taught he was sinless. So now we have Mary and John the Baptist sinless. The RC love to change the true gospel. John the baptist was Jesus cousin and supposedly sinless questioned who Jesus was:And possibly John the Baptist. I say possibly John the Baptist becasue there is a Tradition in the Church that he never sinned becasue he was sanctified in the womb. However, I am certain whether the Church has formally pronounced on that.
In any case----the word "all" is used "all" the time in a general sense. Rarely does the word ever mean "absolutely no exceptions." Given that only three people in salvation history have been known to be sinless: Jesus, Mary, and possibly John the Baptist, I hardly thing 3 exceptions in the entirety of creation would disprove the rule.
But Catholics have never denied that Mary needed a savior. What, if not Christ, do you think Catholics believe the basis of Mary's sinlessness is?
2 When John the Baptist was in prison, he heard what Jesus was doing. He sent his followers.