are you saying there wasn't anything actually wrong with Cain's sacrifice, but God rejected it just 'because Cain is Cain' and Abel was chosen and Cain was not?
then why does God say to Cain
If thou doest well, shalt thou not be accepted?
(Genesis 4:7)
because Cain is Cain' and Abel was chosen and Cain was not?
Yes.
In Christian faith , we the winners/the saveds finally surely say “ the Glory is for God alone “ because we understood well that Salvation is by God’s Grace alone ( this is the goal of creation Isa43:7 ) , the understanding about this premise surely come through understood well too about The chosen ( Eph1:4 ) or we surely understood about the reason “why God hated Esau and loved Jacob even when they not yet be born and did anything ( God chose by His own will not depend on works ).
then why does God say to Cain
If thou doest well, shalt thou not be accepted?
(Genesis 4:7)
In GWT judgment , this case shall be judged.
In that time spirit being who dwelled within Cain shall be judged , and Abel ( spirit of Abel/ the chosen ) will act as the witness ( 1Cor6:3 ) , what is the law shall be used for suing him ?.
Gen4:7 If thou doest well, shalt thou not be accepted? and if thou doest not well, sin lieth at the door. And unto thee shall be his desire, and thou shalt rule over him
This is the only law for Him to judge