12. For there is no difference--or "distinction"
      between Jew and Greek; for the same Lord over all--that is, not God (as CALVIN, GROTIUS, OLSHAUSEN, HODGE), but Christ, as will be seen, we think, by comparing Ro 10:9, 12, 13 and observing the apostle's usual style on such subjects. (So CHRYSOSTOM, MELVILLE, BENGEL, MEYER, DE WETTE, FRITZSCHE, THOLUCK, STUART, ALFORD, PHILIPPI).
      is rich--a favorite Pauline term to express the exuberance of that saving grace which is in Christ Jesus.
      unto all that call upon him--This confirms the application of the preceding words to Christ; since to call upon the name of the Lord Jesus is a customary expression. (See Ac 7:59, 60; 9:14, 21; 22:16; 1Co 1:2; 2Ti 2:22).

JFB.