Why is a backward facing car seat safer for an infant than a seat that faces forward during a collision or abrupt stop?

Why is a backward facing car seat safer for an infant than a seat that faces forward during a collision or abrupt stop?
Its safer for the seat to be facing backwards, because during a collision or an abrupt stop the infant would not be able to slip out of the car seat, and also so the infant will not choke on the car seat's seat belt. It is also safer to have an infant/child to be sitting in the back seat and not in the front passenger seat until the recommended age.