relationship between a man and God should be his private affair which no others should interfere with.
parents have a responsibility on children till age 18 to teach them about life and religion but after that each adult has the authority to make his/her decisions himself, and if he chooses to be closer to God then that's his upbringing and/or choice and if otherwise then we cannot criticize him either.
more than half the time we are very hypocritical on matters of religion. wouldn't like to give examples but im sure you get what im trying to say.
im not saying it was wrong of the baby to say that to his father, because firstly, he's a baby, and secondly it shows his mother has taught him right, but what im saying is your mindset is wrong from the harsh words you chose for someone who does not offer Salah. just praying does not make a man pious.