Sprinkling some water on a baby is absolutely meaningless. An infant is not capable of sin. Catholics also have it wrong on being born again. When a person is old enough to decide on his or her own, they accept Jesus Christ as their personal lord and savior. Forcing a 10 year old into communion is meaningless when the child has no idea what is going on. But, I don’t expect catholics to ever understand. They’re too wrapped up in meaningless (to God) acts that have no bearing on how one achieves true salvation.
The wages of sin is death (mortality).
An infant is mortal.
Thus an infant is sinful.
You confuse sinfulness, a state of being, with a sin, a specific act.
“For all have sinned...” That is pretty encompassing, including those who die in the womb, or after birth.
All are conceived in a state of sin - Original Sin: spiritual separation from God that requires supernatural intercessation to ameliorate.
All. Not some. Not those after an arbitrary so-called age of accountability.
The validity and efficacy of infant baptism - not the same thing, by the bye - is an entirely legitimate debate among well-meaning Christians, but it must not be conflated with the more basic, vital issue.
The sinful state - physical mortality and spiritual separation as a result of the Fall - of an infant is inarguable; to assert otherwise is heresy.