Peter explicitly states that water baptism is NOT what saves us. It is our association with Messiah through which the Spirit (Breath of the Father) dwells within us (good conscience) that is our salvation.
The firstborn of the people were to be sanctified to Elohim. The firstborn of Egypt, both man and beast were killed that night (Ex. 12:12). With that being the case, the firstborn of Israel belonged to Elohim in a special way. The word qadash is translated “sanctify.” It means to consecrate, separate, or set-apart a person or thing from all common or secular purposes for use for service to Elohim.