i'm not surprise if you perceived things as such bro, even i myself almost left my faith in the Judeo-Christian God many years ago for many reasons, one of which is the same thing that we're talking about right now.
you actually answered your own question..
the key words and phrases would be.. " TO ME", "ALL POWERFUL" and "MUST'VE"
point is, it's easy for us to conclude something must have been wrong when we don't know the absolutes of right and wrong
and do we even understand the capacity of an "ALL POWERFUL" being?
i don't know if you've experienced this but when i was a teenager, i grew up hating my parents 'cause of how they were while i was growing up..
now that i have a family of my own, i ended up thanking my parents for i wouldn't be who i am right now if not for them.
i believe when simplified it is the same with God's ways, only in an almost infinitely complex manner. besides, He's suppose to be all powerful and all knowing.
personally, i used to hate God before 'cause i had to go through serious LOADS of CRAP in the past, now i no longer do but the crappy circumstance still surface from time to time..at times even on a daily basis..
like a kid with basic math skills trying to solve an algebraic equation, i could never understand the specifics and reason behind everything..but one thing i'm sure of,
they were for purpose and that purpose was good.
for had i not gone through those edgy moments, i wouldn't have met challenges that ultimately led to maturity and wisdom.
Like death as the capital punishment in the days of Moses, who knows? for us it was just pure Evil but to an ALL KNOWING and ALL POWERFUL God, it meant indulgence and a chance for salvation.
and again by evolution of Salvation, it doesn't mean CHANGE but rather a FULFILLMENT.
if people back then were to be saved by their own actions, Jesus fulfilled it with His sacrifice on the cross.. so no more stoning to death, no more outcasting, no more whatsoever..as Jesus said on the cross. it is done.

Jesus didn't do away the old Laws but fulfilled them instead.
Jesus died on our behalf. Jesus who was without sin became Sin for us, Jesus was the Lamb of God and the sin offering that takes away the sins of the world.
in other words, it is Jesus who gets stoned to death instead of us.
that's what i meant by evolution of Salvation and it never meant CHANGES.