Paul has just concluded his treatise on God's insistence that things must be done his way and how that by trying to "climb up another way" the Jews of the first century failed to obtain the justification that the gentiles obtained because they sought it not by faith:
NIV Romans 9: 10Not only that, but Rebekah’s children were conceived
at the same time by our father Isaac. 11Yet, before the twins were
born or had done anything good or bad—in order that God’s purpose in
election might stand: 12not by works but by him who calls—she was
told, “The older will serve the younger.” 13Just as it is written:
“Jacob I loved, but Esau I hated.” 14What then shall we say? Is God
unjust? Not at all! 15For he says to Moses,
“I will have mercy on whom I have mercy, and I will have compassion on whom I have compassion.” 16It does not, therefore,
depend on human desire or effort, but on God’s mercy. 17For Scripture
says to Pharaoh: “I raised you up for this very purpose, that I might
display my power in you and that my name might be proclaimed in all
the earth.” 18Therefore God has mercy on whom he wants to have
mercy, and he hardens whom he wants to harden.
In other words, obedience is better than sacrifice.
Paul refers then to these "mercies of God" as impetus to throw one's being into service to God as opposed to the Jewish effort to earn favor through works of righteousness by the Torah:
NIV Romans 9: 30What then shall we say? That the Gentiles, who did not
pursue righteousness, have obtained it, a righteousness that is by
faith; 31but the people of Israel, who pursued the law as the way of
righteousness, have not attained their goal. 32Why not? Because they
pursued it not by faith but as if it were by works. They stumbled over
the stumbling stone.
He alludes to another pair of brothers where the elder is refused when he refers to the living sacrifice of the gentiles as an "acceptable" sacrifice:
NIV Genesis 4: 2Later she gave birth to his brother Abel. Now Abel
kept flocks, and Cain worked the soil. 3In the course of time Cain
brought some of the fruits of the soil as an offering to the Lord.
4And Abel also brought an offering—fat portions from some of the
firstborn of his flock. The Lord looked with favor on Abel and his
offering, 5but on Cain and his offering he did not look with favor. So
Cain was very angry, and his face was downcast. 6Then the Lord said to
Cain, “Why are you angry? Why is your face downcast? 7If you do what
is right, will you not be accepted? But if you do not do what is
right, sin is crouching at your door; it desires to have you, but you
must rule over it.” 8Now Cain said to his brother Abel, “Let’s go out
to the field.” While they were in the field, Cain attacked his brother
Abel and killed him. 9Then the Lord said to Cain, “Where is your
brother Abel?” “I don’t know,” he replied. “Am I my brother’s keeper?”
10The Lord said, “What have you done? Listen! Your brother’s blood
cries out to me from the ground. 11Now you are under a curse and
driven from the ground, which opened its mouth to receive your
brother’s blood from your hand. 12When you work the ground, it will no
longer yield its crops for you. You will be a restless wanderer on the
earth.”
NIV Hebrews 11:By faith Abel brought God a better offering than Cain
did. By faith he was commended as righteous, when God spoke well of
his offerings. And by faith Abel still speaks, even though he is dead.
