With that in mind, let us first study the immediate context in which the phrase "the faith of God" is placed and then from there branch into other parts of the Roman epistle. Finally, we will look at the remainder of the New Testament, the larger context, to ascertain if there is anything that helps us to determine what "the faith" and the "faith of God" may truly denote or connote. Already we have seen that at least in Jude 1:3 "the faith" means what I affirm it to mean in Romans 3:3 (and, I might add, in other places in the Roman epistle and in the New Testament).
The Immediate Context
"For he is not a Jew, which is one outwardly; neither is that circumcision, which is outward in the flesh: But he is a Jew, which is one inwardly; and circumcision is that of the heart, in the spirit, and not in the letter; whose praise is not of men, but of God. What advantage then hath the Jew? or what profit is there of circumcision? Much every way: chiefly, because that unto them were committed the oracles of God. For what if some did not believe? shall their unbelief make the faith of God without effect? God forbid: yea, let God be true, but every man a liar; as it is written, That thou mightest be justified in thy sayings, and mightest overcome when thou art judged." (Romans 2: 28 - 3: 4)
The True Jew
The generally accepted definition, one that you would find in any dictionary in the time of Jesus and Paul, defined being "Jew" in regard to 1) birth origin, and 2) nationality, or citizenship, and 3) type of government, and 4) social customs, and 4) religion. As far as the last is concerned, it was more of a national religion, wherein both genuine and false professors grew together like wheat and tares in a field. This definition Paul had problems with and therefore sought to give what would in essence be God's definition of what is the character and description of a "Jew," which is a most important question, for Paul sees only "Jews" as being saved, or as being God's children.
What interpreter can doubt that in these words Paul is discussing this very point? That he begins this section of Scripture by giving a true definition of what it means to be a "Jew"? What is it in the preceding verses that has led Paul to this present point of focus?
In Romans 2:17 Paul begins his contrasts between those who are by nature Jews (who are so by a physical birth and genealogical lineage), with those who are "Jews" in spirit and by a new birth. The apostle John felt a need to say, like Paul here, that the new birth is "of God," but "not of blood" (John 1:13) or as a result of birth nationality.
He says "Behold thou art called a Jew..." (2:17) In this language he calls into question whether those who are "called" or otherwise styled as "Jews" are what the name ought to imply. He puts to the test the question of whether those who are generally recognized as being "Jew" are in truth what the name implies.
His beginning with "Behold" calls the earthly Jew to look deep and seriously, beyond the cloaks and the masks, and with a sense of irony and surprise, to discern between the name and the thing signified by it. His rhetorical or prosecutor style, wherein he interrogates the "Jew" with penetrating questions designed to expose the hypocrisy and self deception of most of those who were in name "Jews," is truly remarkable. And, what does the word "Jew" mean?
"Jew" is derived from "Judah" which means "praise," ("Judah, thou art he whom thy brethren shall praise" - Gen. 49:8) particularly towards Jehovah, but also towards the ideal "Judah" or "Jew," which surely was the Lord Jesus. When the Samaritan woman referred to Jesus as a "Jew" (John 4:9), she no doubt judged him so by general common criteria (as mentioned above), but she did not know at that time that he was "Jew" in the highest sense and worthy of the highest praise. Jesus was superlatively "he whom thy brethren shall praise," but he is one also highly praised by his Father who said out of Heaven - "this is my beloved Son in whom I am well pleased." Further, as Paul shows elsewhere, Christians should also seek the praises of God.
It seems obvious that Paul makes use of the Hebrew meaning of the word "Judah" (or "Jew"), meaning praise, as before noticed, to substantiate his spiritual definition of those terms. Hypocrites and lost Gentiles do not fit the description of "praise," not being the characters of whom God speaks well. When he concludes his list of contrasts between carnal and spiritual Jews he says "whose praise is not from men but from God," echoing the words of the Lord Jesus.
If being a "Jew" by divine judgment and estimation were by carnal procreation, circumcision, or by being citizens of the earthly commonwealth of Israel, or by nationality, or by keeping an external devotion to the Hebrew religion, then praise would come from men, but not from God. Praise is both directed to God in people becoming spiritual Jews and Israelites but also from God to those same people as they are daily made in heart and character worthy of the kingdom of God.
Paul, in his questioning of Jewish religious hypocrites (beginning in verse 17), simply imitates the method of the Lord Jesus himself, who often interrogated such impostors with piercing questions that were designed to convict and persuade, as well as to expose them. Said Jesus of these "Jews": "For they loved the praise of men more than the praise of God." (John 12:43) And he also said:
"How can you believe if you accept praise from one another, yet make no effort to obtain the praise that comes from the only God?" (John 5:44 NIV)
These words show that it should be the desire of Christians to obtain God's praises, for him to think and speak well of us (what it literally means for God to bless us), to honor and approve of us, for him to say to us "well done, thou good and faithful servant" (Matt. 25: 23), etc. Jesus is our example, and though we cannot live up to the name of "Jew" as he did, yet we strive to do so, praying for grace.
Paul does speak of those, including himself, "who are Jews by nature," in Galatians 2:15, or by a physical birth, and in Romans 9:3 he will refer to them as "my brethren, my kinsmen according to the flesh," and who, naturally speaking, and by carnal definition, are "Israelites." But, then, in order to further show that he is redefining what it means to be a "Jew" or an "Israelite," or to be of "the seed of Abraham," he says pointedly: "For they are not all Israel, which are of Israel: Neither, because they are the seed of Abraham, are they all children." (vs. 6,7)
In redefining "Jew," "circumcision," "seed of Abraham," "Israel," "children of God," "elect," etc., he describes the persons designated by these terms in the way that God has always intended that they should be understood and interpreted. Not only are these titles of character defined properly in this epistle, and from God's perspective, or from his heavenly dictionary, but other words, familiar to Jews who were familiar with the Scriptures, such as "righteousness," "justness," "law," etc., are also accurately defined by the inspired apostle.
The Man of "no faith"
The Jews whom Paul regards as being in the category of those who "believed not," or who "lack faith," it is in respect to "the oracles of God." When they are described as those who have "no faith" he does not mean that such persons have no religious beliefs, or are irreligious. People today may say in vernacular speech that such a man "he has no faith," meaning he has no religion. It rather means that such people have no genuine or true faith. All religious faith outside of that revealed by the Hebrew God is "no faith," and even the Hebrew "faith" of the Jewish hypocrites was likewise actually no faith at all. The word "true" or "truth" (alḗtheia) does not only refer to verity or veracity as to facts, but also as to what is "real" as opposed to what is illusion. The real Jew has real "faith," not only objectively so, but subjectively too.
The lost Jew can find no justification for his hypocritical "faith," or apostate religion, and the lost Gentile can find no legitimate excuse for his pagan or polytheistic "faith." A person is esteemed a "Jew" in God's sight by his allegiance to God and his word and to that "pure and uncorrupted religion" (James 1:27) of which he is the author. If one is heeding doctrines of men and demons, as we have seen, then he has a religion and a faith but they have what is not true or real.
In condemning both classes Paul points to the standard for judging the reality or truthfulness of the faith of any man. Both condemned classes are assumed to be religious in nature, to have views of God, or a system of organized divinity, and to practice religion. The atheist is not particularly in view, although it can be argued that even atheists have a "faith" or "belief system."
The Oracles = The Faith
In the immediate context "the faith" that is "of God," is associated with 1) "the oracles," which are likewise said to be "of God," and with 2) the "sayings" of Deity, and 3) with God being "true" in his communications.
Since the interpretation of Genitive nouns largely depends upon the "context," then the presence of the above three items weigh heavily in favor of my thesis. Not only do I affirm that "the faith of God" in Romans 3:3 means the same thing as in Jude 1:3 but that it also means the same thing as "the oracles of God." Who cannot see the parallel expressions "the faith of God" and "the oracles of God"?
Both expressions are in the same syntax construction: HEAD NOUN then GENITIVE NOUN. In "the oracles of God" it seems clear that we have an Ablative Genitive which indicates both source and kind. This could lend weight to the view that "the faith of God" is also such. In this case we would translate as follows: "shall their no faith make the faith that comes from God ineffectual?" This is entirely plausible and a better translation than that which says "shall their faith make the faithfulness of God ineffectual." Further, if it is Ablative Genitive, like "oracles of God," then the contrast is on that "faith" which finds its source in God versus that hypocritical or heathen "faith" that is "of" or "from" men and from their false deities. The pagan Gentiles had their "oracles," originating from their imagined deities, and many of them prove to be failures and falsehoods, but not the Hebrew oracles.
The faith of men and of carnal Jews may and will certainly fail or prove ineffectual, but not that faith which has its origin in God and his word and oracles as the object of trust and belief. The apostasy or hypocrisy of some does not prove that God or his word has failed. God is not at fault nor is his divine revelations. The fact that some trusted and believed those oracles and that faith proves that they had not failed. Besides, Paul has already said that both Jews and Gentiles are "without excuse," and has justified God in affirming that he had given to the Jews every "advantage" by giving them the blessed oracles. He later elaborates even further upon these advantages and means of grace in Romans nine when he says "to whom pertains the adoption, and the glory, and the covenants, and the giving of the law, and the promises," etc.
Thus far we have three expressions that virtually mean the same thing. They are 1) "the oracles of God" and 2) "the faith of God," and 3) "the word of God." I contend that though three different expressions are used, the apostle is still substantially referring to the same thing, to that system of truth and revealed religion that God has given through the prophets, and now chiefly and additionally by Christ and his apostles.
What is it that is being questioned or doubted by carnal Jews in their verbal confrontations with the apostle? Most generally in this epistle Paul has an antagonist in mind when he raises questions or discusses theological questions. Sometimes these adversaries were referenced specifically, while at other times, as here, they and their religious notions are clearly in the background. Is it not his teaching about what constitutes a "Jew" and "child of Jehovah"?
When Paul asks "shall their no faith make the faith of God ineffectual?" he could just as well have kept the expression first introduced, i.e. the "oracles of God," but not wanting to be repetitious, but more varied in his descriptions, he substitutes "faith of God" for it. So, with this in mind let us now read the sentence, substituting "the oracles of God" in place of "the faith of God" and discover if there is any discovery to be made thereby. "Shall their no faith make the oracles of God ineffectual?"
But, besides not wanting to repeat the same adjectival noun again, he also has a superior reason for changing how he styles the Hebrew Scriptures and religion in verse three over how he styled it in verse one. He wants to substitute "faith" for "oracles" because it is a better word to set in opposition to the unbelief or no faith of the carnal fleshly Israelite. The word "oracle" alludes to the fact that God has orally "spoken" or said something. This fact connects with Paul's citation of the Psalmist who spoke of God being "justified" in his "sayings." Is not the "sayings" an allusion to the "oracles"? Are not his "sayings" also the same as his "word"?
The Faith of God = The Gospel of God
"Paul, a servant of Jesus Christ, called to be an apostle, separated unto the gospel of God." (Rom. 1:1; see also Rom. 15:16)
"For I am not ashamed of the gospel of Christ..." (Rom. 1:16; see also 15:19)
I affirm that "the gospel of God" again refers much to the same idea as are "the oracles of God," or "the faith of God," or "the word of God," or "the truth of God" and that these expressions, all being used within the same general context, gives much credence to my thesis about what is meant by "the faith of God."