Be that as it may, what does Witherington have to say about the idea that Christianity was invented by Paul?
One can say that Paul was a catalyst which helped lead the Jesus movement out of Judaism and into being its own religious group. Paul was not the inventor of Christianity, but in some senses he was its midwife, being most responsible for there being a large number of Gentiles entering this sectarian group and not on the basis of becoming Jews first (i.e. having to keep kosher, be circumcised, keeping the Sabbath) which in turn changed the balance of power in the movement everywhere in the empire except in the Holy Land.
At the end of the day, Paul's view of the Mosaic law and whether it should be imposed on Christians most clearly reveals that Paul understood that being in Christ meant something more and something different from being "in Judaism". This is why in an elaborate argument in Galatians Paul compares the Mosaic law to a child minder or a nanny, who was meant to oversee the people of God until they came of age, but now that Jesus has come they are not under that supervisor any more (see Gal. 4). Paul even goes so far as to say that one of the main reasons Jesus came born under the law was to redeem those under the law out from under its sway (see Gal. 4:5). Those under the law are seen as being in bondage to it, until Christ came and redeemed them. Now this is clearly enough sectarian language, the language of a split-off group from Judaism. Paul insists in Galatians 2:21 that a person could be set right, or kept right with God by the observance of the Mosaic law then "Christ died for nothing." He even urges his converts "every man who lets himself be circumcised that he is obligated to obey the whole law" (Gal. 5:3 NIV). This is also why, in a salvation historical argument in 2 Corinthians 3:7-18 he speaks of the Mosaic law, and even the Ten Commandments, as a glorious anachronism, something which was glorious in its day, but which is rapidly becoming obsolete.
In the end, one can say that Paul was a shepherd leading God's people in new directions and through uncharted waters to a new promised land where Jew and Gentile would be united in Christ on the very same basis and with the very same discipleship requirements. Though Paul did not call this end result Christianity, he more than any other of the original apostles was responsible for the birthing of the form of community which was to become the early church. Though he did not invent its doctrines or even its ethics, he most consistently applied its truths until a community that comported with these truths emerged.
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