TRUTH Romans 15:8-9

For I tell you that Christ has become a servant of the Jews on behalf of God's truth, so that the promises made to the patriarchs might be confirmed and, moreover, that the Gentiles might glorify God for his mercy. As it is written: "Therefore I will praise you among the Gentiles; I will sing the praises of your name." (2 Samuel 22:50)

For I tell you that Christ has become a servant of the Jews on behalf of God's truth 
Matthew 15:24  He answered, "I was sent only to the lost sheep of Israel."
Acts 3:24-26  "Indeed, beginning with Samuel, all the prophets who have spoken have foretold these days. And you are heirs of the prophets and of the covenant God made with your fathers. He said to Abraham, 'Through your offspring all peoples on earth will be blessed.' (Genesis 22:18; 26:4) When God raised up his servant, he sent him first to you to bless you by turning each of you from your wicked ways."

so that the promises made to the patriarchs might be confirmed 
2 Corinthians 18-20  But as surely as God is faithful, our message to you is not "Yes" and "No". For the Son of God, Jesus Christ, who was preached among you by us--by me and Silas and Timothy--was not "Yes" and "No", but in him it has always been "Yes". For no matter how many promises God has made, they are "Yes" in Christ. And so through him the "Amen" is spoken by us to the glory of God.

and, moreover, that the Gentiles 
Romans 3:29-30  Or is God the God of the Jews only? Is he not the God of the Gentiles too? Yes, of Gentiles too, since there is only one God, who will justify the circumcised by faith and the uncircumcised through that same faith.

might glorify God for his mercy 
Matthew 9:8  When the crowd saw this, they were filled with awe; and they praised God, who had given such authority to man.
2 Samuel 22:50  "Therefore I will praise you, LORD, among the nations; I will sing the praises of your name."
Psalm 18:49  Therefore I will praise you, LORD, among the nations; I will sing the praises of your name.

(parentheses are mine)

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