If some did not believe; if some did remain in infidelity, Acts 28:24, if they would give no credit to the oracle, and to the promise of a Messiah. The faith of God; i.e. the truth and faithfulness of God, Psalms 33:4. The whole verse is another prolepsis. The implied objection is this, That the Jews are nothing the better for these oracles, or have no advantage by them, if by unbelief they have rendered themselves unworthy or incapable of benefit by them. The answer to this is anticipated by propounding another question; Can the infidelity of some be any hinderance of God's performing his promise to others, to his chosen ones? The interrogation is a negation, q.d. It cannot be, as the following words show: see 2 Timothy 2:13.
Related Commentaries of Romans 3:3
Romans 3:3
3 For what if some did not believe? shall their unbelief make the faith of God without effect?