Christians, in contrast, have an addendum to the contract --UMmm...
not exactly, for that OLD contract was BROKEN - there's NOTHING tht can be added to or taken away from it.
NIV Galatians 3:11-19
11. Clearly no one is justified before God by the law, because, "The righteous will live by faith."
12. The law is not based on faith; on the contrary, "The man who does these things will live by them."
13. Christ redeemed us from the curse of the law by becoming a curse for us, for it is written: "Cursed is everyone who is hung on a tree."
14. He redeemed us in order that the blessing given to Abraham might come to the Gentiles through Christ Jesus, so that by faith we might receive the promise of the Spirit.
15. Brothers, let me take an example from everyday life. Just as no one can set aside or add to a human covenant that has been duly established, so it is in this case.
16. The promises were spoken to Abraham and to his seed. The Scripture does not say "and to seeds," meaning many people, but "and to your seed," meaning one person, who is Christ.
17. What I mean is this: The law, introduced 430 years later, does not set aside the covenant previously established by God and thus do away with the promise.
18. For if the inheritance depends on the law, then it no longer depends on a promise; but God in his grace gave it to Abraham through a promise.
19. What, then, was the purpose of the law? It was added because of transgressions until the Seed to whom the promise referred had come. The law was put into effect through angels by a mediator.