If faith is my response to what God has done, where does faith come from? If it comes from within, if it is my own contribution, then it could become a ground for my boasting.

Paul makes three points regarding justification:

1. Verses 27 to 28: Justification is not earned. It is not based on keeping the law. Justification is through faith, and faith is God's gift. Otherwise justification would be a work. If it was a work, it would provide grounds for boasting. So, boasting is excluded.
2. Verses 29 to 30: Justification means that God is not some localised deity having oversight and interest in the Jews alone. Justification is by faith. It is not by keeping the law or circumcision. Faith can be found in either the circumcised Jew or the uncircumcised Gentile.
3. Verse 31: In justification, God does not set aside His own justice. He does not close His eyes to broken law (see Proverbs 24:24). He does not nullify the law. Rather, our faith is directed to the work of the One who fulfilled the law's demands. The law is upheld by the provision of a perfect life offered (redemption) and God's just wrath absorbed (propitiation).

Thus, in justification, God is seen to be central. He is the source of faith that we need to link us to the work of Christ. He is the expansive God with no limited national interest. He is totally just and yet, as justifier, He is wonderfully merciful.

The early theologian Saint Augustine prayed, ″O God, demand what You will, but supply what you demand!″ God demands perfection and He meets that demand in the provision of His Son.