Baptism is an ancient ritual performed when someone becomes a Christian or when some baby's parents decide to make him/her into a Christian.
The Bible has stated that Baptism is required to go into Heaven, but what would become of those infants that aren't baptized? Furthermore, what about the children that are in their mothers wombs and die (around 8 months of pregnancy)? Up till the Middle Ages and beyond Christians believed those infants would be damned due to Original sin. They hadn't sinned themselves but the sins of Adam and Eve would condemn them.
Nothing indeed can be more curious, nothing more deeply pathetic, than the record of the many ways by which the terror-stricken mothers attempted to evade the awful sentence of their Church. Sometimes the baptismal water was sprinkled upon the womb; sometimes the still-born child was baptized, in hopes that the Almighty would antedate the ceremony; sometimes the mother invoked the Holy Spirit to purify by His immediate power the infant that was to be born; sometimes she received the Host or obtained absolution, and applied them to the benefit of her child. For the doctrine of the Church had wrung the mother's heart with an agony that was too poignant for even that submissive age to bear." Rationalism in Europe, i, 362-364. 
No matter how faithful Christians are to God, they would not be able to ascend into heaven if they weren't baptised or if there were baptised the wrong way. Christians don't even agree how baptism should be done:-
- Some Christians baptise by total immersion, others just sprinkle water.
- Some Christians do a ceremony first which they believe makes the water holy. others believe the ceremony itself makes the water holy.
- Some Christians baptise in the name of the Father, son and Holy Ghost, others baptise in the name of Jesus only.
Fortunately there's no reason to believe in the dictatorial, unmerciful God of Christianity.
Dunking water on the head of a baby or adult, alternatively immersing the aforementioned baby/adult in water is a ritual that’s relatively harmless in itself unless there are germs in the water. Despite this the ritual is all too often the start of a process or part of a process that erodes critical thinking and encourages unquestioning faith.
- How can you tell the difference between Christianity and a scam?
- How can you tell the difference between Christianity and an abusive relationship partner?