What is the purpose or theology behind the practice of infant baptism?

In the early years of the Christian movement, only adults were baptized, and then only after extensive preparations lasting as long as three years. Those baptized were literally taking on a new life. As time went on, the age of baptism became younger and younger. When superstition and high infant mortality raised fears of eternal damnation, it became the norm to baptize infants as soon as possible after birth.

One feature of the Protestant Reformation was to move away from infant baptism, on the theory that baptism only made sense if the person comprehended what was happening. Some Protestant traditions, however, continued infant baptism, believing that baptism isn't an intellectual or spiritual accomplishment, but a new state that one spends an entire life living into.

My tradition, the Episcopal Church, affirms infant baptism. My belief is that baptism can occur at any age, that God's love is a given, not a prize, and that self-awareness as a Christian matures and changes as we mature and change.