Larger Catechism
Q 31. With whom was the covenant of grace made?
A. The covenant of grace was made with Christ as the second Adam, and in him with all the elect as his seed.1
Galatians 3:16
Now the promises were made to Abraham and to his offspring. It does not say, “And to offsprings,” referring to many, but referring to one, “And to your offspring,” who is Christ.
Romans 5:15-21
But the free gift is not like the trespass. For if many died through one man’s trespass, much more have the grace of God and the free gift by the grace of that one man Jesus Christ abounded for many. And the free gift is not like the result of that one man’s sin. For the judgment following one trespass brought condemnation, but the free gift following many trespasses brought justification. For if, because of one man’s trespass, death reigned through that one man, much more will those who receive the abundance of grace and the free gift of righteousness reign in life through the one man Jesus Christ.
Therefore, as one trespass led to condemnation for all men, so one act of righteousness leads to justification and life for all men. For as by the one man’s disobedience the many were made sinners, so by the one man’s obedience the many will be made righteous. Now the law came in to increase the trespass, but where sin increased, grace abounded all the more, so that, as sin reigned in death, grace also might reign through righteousness leading to eternal life through Jesus Christ our Lord.
Isaiah 53:10-11
Yet it was the will of the Lord to crush him;
he has put him to grief;
when his soul makes an offering for guilt,
he shall see his offspring; he shall prolong his days;
the will of the Lord shall prosper in his hand.
Out of the anguish of his soul he shall see and be satisfied;
by his knowledge shall the righteous one, my servant,
make many to be accounted righteous,
and he shall bear their iniquities.Isaiah 59:20-21
“And a Redeemer will come to Zion,
to those in Jacob who turn from transgression,” declares the Lord.“And as for me, this is my covenant with them,” says the Lord: “My Spirit that is upon you, and my words that I have put in your mouth, shall not depart out of your mouth, or out of the mouth of your offspring, or out of the mouth of your children’s offspring,” says the Lord, “from this time forth and forevermore.” (ESV)