Muslims. Do you actually believe this?? Every child is born…

Muslims. Do you actually believe this??
Every child is born in a state of islam(fitrah), which means total submission and dependence on allah?
If that’s true, and EVERY child begins in islam, then WHERE did Christianity come from??
No human could have invented Christianity! The only way Christianity could have been introduced is if GOD gave it to us!

islam is false again.?