30 since there is only one God, who will justify the circumcised by faith and the uncircumcised through that same faith.

Read Romans 3:30 Using Other Translations

Seeing it is one God, which shall justify the circumcision by faith, and uncircumcision through faith.
since God is one--who will justify the circumcised by faith and the uncircumcised through faith.
There is only one God, and he makes people right with himself only by faith, whether they are Jews or Gentiles.