Why can't salvation be worked for or merited?
Salvation cannot be worked for or merited because it is God's gift, given by grace through faith, not of yourselves. If it were earned by works, it would no longer be a gift. God imputes righteousness without our doing anything, as illustrated by Israel, who could not do a thing.
Les explains that Ephesians 2:8-9 teaches salvation is by grace through faith, and that not of yourselves—not anything you and I can do. It is the gift of God. He asks whether anyone works for or merits a gift; never, because then it would no longer be a gift. Salvation is something you do not work for. Likewise, Romans says God imputes righteousness without works, without our doing a thing, and Israel on the shore of the Dead Sea couldn't do a thing.
For by grace are ye saved through faith; and that not of yourselves: it is the gift of God: