Atheists: is a newborn baptized baby an atheist or a born again Christian yet to blossom?

Considering that fact that it will most likely take on the religion of its parents, as you did, then the chances are that it will not be Christian (2/3 of the people on the planet are not). Random chance at birth will determine its religion, and which god or gods it believes in. In some cases, this religious indoctrination fails, and the child makes up its own mind.