From the time of the ancient Near East, the term covenant (berit in Hebrew) has referred to a bond of agreement and of affection. Solemnized by means of sacrifice, covenants bound one person to another, one community to another, as well as a people to their god. Christianity and Judaism perpetuate primordial, covenantal commitments to this day as the seal of what they have agreed with the God of Abraham, Isaac, and Jacob, and how they engage with him.

Yet in important ways the two religions disagree in regard to how this God should be served as well as by whom. No thinker better exemplifies these differences than Paul does. Paul may be said to embody the covenantal argument that divides Judaism and Christianity.

The largely non-Jewish Christianity that emerged by the second century of the Common Era hailed Paul as “the Apostle,” the preeminent teacher in a small, marginal, but growing movement. Paul had been born in Tarsus, a major center of Stoic thought during the first century, so his appeal to an increasingly Greco-Roman religious movement after his death is not surprising. Traces of Stoicism are evident in some of his most famous contributions to theology, such as the concept of believers forming a single “body” and his identification of a divine principle uniting the entire kosmos. Nonetheless, prior to his conversion by his own testimony Paul was a Pharisee advanced in the learning of his day; his commitment to Pharisaism had even drawn him to reside in Jerusalem.

A keen intellectual, he came to see Judaic teaching as the true wisdom of Greco-Roman philosophy, and philosophy as the key to Judaism. He proved to be the catalyst that produced a hybrid of Judaism and philosophy by means of his claim that he had encountered the Son of God in a visionary experience near Damascus: the resurrected Jesus had sent him to bring the divine message, the ancient wisdom of the prophets, to the Gentiles (Galatians 1:15–17). Paul claimed that Christ trumped the wisdom of the philosophers and at the same time fulfilled the Torah of Judaism. His assertions were controversial and difficult for Paul to sustain in the face of opposition outside Christianity and more particularly within Christianity. In his own time he was in a distinct minority, sometimes in a minority of one, and there were several alternatives to every statement of principle he made. Yet his covenantal theology has proven to be central to an appreciation of Christianity's distinctive character.

This theology was forged in the crucible of the early Christian practice and experience of baptism. Throughout the course of his life after his conversion, Paul struggled with the issue of what it meant, in terms of the Torah, to be baptized into Christ. Paul was not the only Pharisee who had become a follower of Jesus. (We can’t say they were “Christians” in these earliest years of the movement, since that term did not yet exist, and was slow to be accepted. Paul himself never used it in all his letters.) Some Christian Pharisees insisted that baptism meant that circumcision became obligatory for non-Jews who accepted Christ. Paul famously denied that. He maintained that Jews should continue to be Jews and that Greeks should continue to be Greeks; once baptized, those groups together made up what Paul called “the Israel of God”(Galatians 6:16).

This was far from a common sense view, because it involved a profound redefinition of “Israel.” Paul insisted that the fact of believing in God, by itself, made a person a child of Abraham. Evidence from the time indicates that Paul was unique among leaders of Jesus’ movement in this insistence. Even today, Christians shy away from referring to themselves as “Israel”– although Paul did so emphatically. “Church” is their most commonly used generic designation, deriving from the word for an assembly in Greek (ekklesia); “body of Christ” is the preferred theological designation. “People of God” is growing in usage among Christians and approaches Paul's definition of “Israel,” while stopping short of embracing his definition entirely.

To Paul's mind, God makes no distinction between Jews and Greeks; each side is to maintain its distinctive customs and social identities while being “the Israel of God.” So it is wrong – a vulgar, often repeated parody – to say that Paul wanted Jews to stop observing the Torah. He denied that was his position in so many words (1 Corinthians 9:19–23) as well as by his deeds. After all, his final arrest in the Temple occurred because he was offering sacrifice there in accordance with the Torah.

Yet for Paul, the act of believing in God through Christ made all people – whether Jews or not, whether they committed to keeping the whole Torah or not –“sons of Abraham”(Galatians 3:7) and therefore Israel. The obvious problem with that claim, however, is that, while it does not tell Jews to stop keeping the Torah, it does explicitly deny that God uses the Torah in its completeness as the sign of his covenant with his people, Israel. Paul taught that the Torah applies comprehensively to Jews, to Israel after the flesh (1 Corinthians 10:18, cf. vv. 1–4), but that beyond them its authority is limited.

Controversy with other teachers within Jesus’ movement over whether Gentile Christians needed to keep the Torah caused Paul to think back to a principle he derived from his own conversion. Here his covenantal theology becomes searing in its implications for understanding how Christianity and Judaism disagree. Paul argued that the covenant sealed on Sinai is a partial revelation of God. Paul speaks of Sinai in his letter to the Galatians, written some twenty years after his conversion. He locates the mountain where the Torah was given in Arabia (a place he had actually traveled to; Galatians 1:17), but he does this not to praise the Torah, but to bury it in comparison to another revelation.

Paul compares Sinai to Hagar, the slave woman Abraham took as a concubine. For him, Sinai represents bondage, Jerusalem as burdened by law, while the heavenly Jerusalem, represented by Sarah, is free (so Galatians 4:22–26):

There was a world of torment for Paul in the discovery that the covenant with Moses that he served and made his ideal, the cornerstone that he believed in, had been superseded. His own maternal metaphor in writing to the Galatians suggests that he experienced a heartache like finding your mother is not your true mother.

To Paul, God's Son, revealed within the believer, opened the font of Spirit, so that the promises to Israel could be fulfilled in a “Jerusalem above” that takes the place of “Jerusalem now” in his affections. Writing to communities of Christians in Corinth a couple of years after he wrote to the Galatians, he referred in a stunning image to the significance of Moses. You might expect him to compare Jesus to Moses, and even that would have been an extraordinary argument within the Judaism of the period. But he doesn’t go that way. Instead, he compares himself to Moses.

The Torah says that Moses veiled himself after meeting God on Sinai, to protect the Israelites from the glory that was revealed in his face (Exodus 34:32–25). In a calculated reversal, Paul makes the veil into something that needs to be taken away. The veil is no longer the sign of Moses’ glory in the Torah and becomes the proof that Moses conveyed glory only indirectly. This veil was as approximate and temporary as the tissue of this world. Vision and baptism put believers, as they had put Paul, face to face with God (2 Corinthians 3:14–18):

Paul claimed he looked in the same direction that Moses did, and saw directly what only glimmered behind the Mosaic gauze – the image of God in Christ, the source of glory that transformed Paul in a way that made him directly comparable to Moses.

From the point of view of received Judaism, whether ancient or modern, Paul's equation of himself to Moses seems inconceivably arrogant. But in Paul's experience, and therefore in his mind, the encounter with the Messiah, the uncovering of the divine Son within him, was an immediate confrontation with God. Living with his own visions and revelations (as he called them; 2 Corinthians 12:1), he came to the opinion that they were tablets of a covenant more binding than the covenant with Moses, freer and more genuine – after all, they came directly from the Jerusalem above in heaven.

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While the Temple in Jerusalem still stood, the starkly different covenantal theologies of Judaism and Christianity – for all the tensions between them – could nonetheless converge in the same place. Israelite protagonists of these views – and their many variants – offered sacrifice to their common God there. But with the destruction of that Temple by the Romans, covenantal theologies that were already sharply different became mutually exclusive.

In a document that circulated with the Mishnah (Abot 1:2) long after the destruction of the Temple, the following aphorism is attributed to Simeon the Righteous, who lived well before the destruction of the Temple:

These words were remembered after the Romans burned the Temple in 70 CE and then dismantled what remained of it in 135 CE. The Romans had removed a cosmic pillar, but in the Rabbinic view the Torah and the deeds of living kindness it framed permitted the covenant with Israel to endure to the benefit of humanity as a whole.

The Torah, in other words, became the unique vehicle of the promises to Abraham, Isaac, and Jacob. Within its wide diversity, Rabbinic literature celebrates the capacity of the Torah to convey the very thoughts of God, such that Israelites can share divine joy in creation and the creator's own joy. The Bavli or Babylonian Talmud provides a typical expression of this central, animating principle (Bavli tractate Erubin 54a-b):

The deliberative joy of both observing and maintaining the covenant rooted in the Torah characterizes Rabbinic Judaism.

Also from the period after the destruction of the Temple (c. 95 CE), the Epistle to the Hebrews explains that, in any case, the Temple on earth was only a copy – a shadow of the heavenly sanctuary. That heavenly sanctuary is eternal, and its unique priest and victim is Christ, who also is eternal, not at all to be reduced to what we would call the historical Jesus.

According to this argument Moses on Sinai had from a great remove seen the Throne of God, which was then approximated on earth in the Temple. Hebrews called that approximation the “first covenant,” and said that its time has passed. The heavenly sanctuary offers us a “new covenant”(9:1–15). When Christ died a sacrificial death he revealed that true sanctuary in heaven (9:24) and its truth, palely reflected in Israel's institutions, is accessible to all who believe in Christ. Divine vision, the sanctification to stand before God, is in Hebrews the goal of human life. The only means to the perfect, new covenant is loyalty to Jesus as the high priest who completes the sacrifice that the practices of Israel foreshadowed but could not accomplish.

In exchange for the deliberative joy of the covenant on Sinai, Christianity came to offer the joys of a Jerusalem above. But this joy came to humanity at the price of suffering. In the Gospels Jesus tells his followers, “If anyone would follow after me, let him deny himself, take up his cross, and follow me”(Mark 8:34). The Passion in the Gospels reflects the liturgical practice of Christians during the first century, who recollected Jesus’ suffering during Lent, when they prepared new believers for baptism and committed themselves afresh to walk in the footsteps of Christ. The Passion is at the heart of Christian identity, because the path of Christ is opened to all who will follow him to his resurrected glory.

Near the same time that R. Hiyya bar Abba said R. Yohanan found the Torah in a fig, St Augustine of Hippo discovered in the Lenten discipline of imitating Christ the central theme of human redemption (Sermon 206.1):

The covenantal divide Judaism and Christianity trace in relation to one another helps us to discern a change of emotional tenor as one moves from Judaism's covenant to Christianity’s. The Torah offers an access that is as deliberative and engaged in its joy, as the joy of Christianity delights in the interruption of human mortality. Which of these joys will prove to be heaven’s? Are the two somehow inherent in one another? Our two religions know themselves better by the way of comparison, and by mutual understanding they better acquire the patience to await answers they themselves cannot give, because they are God's alone.