AC 3325 - slaying the firstborn

AC 3325 [12]
... when a person enters into the arcana of faith,
and no longer believes anything
but that which he can apprehend
in accordance with the senses and memory-knowledge -
he then perverts and extinguishes the things of the doctrine of faith,
and especially the things of charity.
This is what is represented in the internal sense by
the firstborn of men and the firstborn of beasts in Egypt being slain...