"But," objects the Replacement Theologist, "doesn't Paul say, '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'?" (Rom. 2:28-29).
Indeed he does, but you completely take this statement out of context if you think that he's therefore saying that a Gentile Christian is the "real Jew."
In the opening chapters of Romans, Sha'ul is establishing that "all have sinned and fallen short of the glory of God" (3:23). He starts by demonstrating the sinfulness of the pagan Gentiles (1:18-2:8), then goes on to show that the Jews are also under God's judgment (2:17-3:23). Where the (pagan) Gentiles are condemned because though they have an innate knowledge of God and an innate knowledge of what they consider to be sin when it is committed against them but nevertheless worship the n0-gods and do not repent of what they know to be evil, the Jew is condemned by the Law of the Torah. Both are judged according to the light that God has given them, and both are found wanting.
In 2:17, Sha'ul begins, "Behold, thou art called a Jew, and restest in the law, and makest thy boast of God . . ." This marks the transition: No longer is Sha'ul establishing the guilt of the Gentile; now he is addressing his own people, warning them that they have no reason to boast. Ergo, when he is addressing the issue of, "Who is a real Jew?" he's not even touching on the issue of the status of Gentile believers!
There is an old Jewish tradition that Abraham will let no circumcised Jew suffer condemnation to Ge'Hinnom (Gehenna, or Hell). Sha'ul here seems to be addressing that tradition. To the Jew that is depending on his circumcision, his Jewishness, and the fact that he knows the Torah to save him, Sha'ul writes, "Thou therefore which teachest another, teachest thou not thyself? thou that preachest a man should not steal, dost thou steal?" (2:21). In other words, do you practice what you preach? "For circumcision verily profiteth, if thou keep the Torah: but if thou be a breaker of the Torah, thy circumcision is made uncircumcision" (v. 25). In other words, if you go about breaking the Torah, you might as well be a pagan Gentile.
It may be thought that by "circumcision of the heart," Sha'ul is saying that only Christians--or at least only Christian Jews--are real Jews, since the heart is circumcised by the Spirit (v. 29, Col. 2:11). However, this presupposes that circumcision of the heart is a New Covenant concept connected to the giving of the Spirit at Shavuot (Pentecost). Not so--in fact, there are repeated commands in the Tanakh for Israel to circumcise their hearts (Deu. 10:16 & 30:6 and Jer. 4:4). The idiom therefore does not refer to being "born-again in the Spirit" per se--it means to internalize the external rite. A true Jew is not just one who was born to Jewish parents and circumcised on the eighth day, or who just goes through the motions for the sake of appearances. A true Jew is one who lives his Jewishness, keeping God's mitzvot (commandments) and making them a part of himself, doing so not for the praise of men, but for the praise of God. (Sha'ul is employing a pun here, as Y'hudah means "Yah's Praise.")
Therefore, I don't think that Sha'ul was addressing the issue of faith in the Messiah at all, at least not at this point in his letter. Rather, he seems to be addressing the Hellenized Jew, the one assimilated in all but name. He may even be addressing the synagogue-going Jew who just shows up for the sake of community appearances, the praise of men. But he is not, in my mind, addressing the God-fearing, Torah-keeping (albeit imperfectly) Jew who had not yet come to a conclusion about whether the Messiah had truly come.
On the other hand, he certainly was saying that the truest expression of Jewishness was to put one's trust in the Messiah of Israel! He was also issuing a challenge to his brothers of blood to look at those Gentiles who "have not the Torah . . . [but] shew the work of the Torah written in their hearts . . ." (Rom. 2:14, 15). The reference to the Torah being written on their hearts is a clear reference to the fact that these Gentiles were partakers of the New Covenant in the Messiah (cf. Jer. 31:33). He was challenging his people to observe the Gentile believers and see that they did indeed keep the Torah better than many Jews even without formal instruction as evidence of the work of God's Spirit. (Remember that the Jews had been expelled from Rome for a time, leaving the Gentile believers without those from whom they would normally learn the Scriptures from; Acts 18:2.) Where under the Mosaic covenant, men were to carry out the external actions and internalize them, under the New Covenant YHVH puts His Spirit in us to convert us internally first, and then this internal conversion comes out in our actions.
Does this mean, as some claim, that the external rites like Passover, tzitzit, etc. have no value? Hardly. Do we claim that because we have received Yeshua in the Spirit that the Lord's Supper and baptism have no more meaning? "But those aren't rituals, they're sacraments!" Potayto, potahto. A sacrament is just "[a] rite believed to be a means of or visible form of grace" (Dictionary.com), and the Catholic Encyclopedia agrees that the rituals of the Torah were "the sacraments of the Mosaic Law." Trying to avoid the fact that even those who most strenuously object to any form of the "ceremonial law" still believe that rituals have their place in the New Covenant by playing word games is a losing proposition. (See Why the New Covenant Doesn't Do Away With the Torah for more on this subject.)
So then, what does this mean for us today?
First, it means that we Gentile Christians can no longer use Romans 2-3 to support Replacement Theology, since Sha'ul is addressing the subject of what makes a Jew, not whether a Gentile should be considered a "true" Jew.
Secondly, we Gentile Messianics should stop fixating on trying to prove that we're "really" Jewish, by bloodline or otherwise. Instead, we should concentrate on showing the evidence of the Spirit in our lives by keeping Torah in such a way that a Sha'ul could point to us for an example. That most especially means loving our Jewish neighbors, whether or not they accept us.
Next: Is the Church an Enemy of the Gospel For its Own Sake?