Back to the issue of Paul being a liar or a true apostle...
Perhaps the issue, as the "New Perspective on Paul" states, is not so much that Paul led a sect of lawlessness, but rather that the sect of Lawlessness used Paul's writings.
There is a noted interpolation for example that only the KJV corrects in 1 Corinthian 9:20 ("Though I myself am not under the Law"). That could be a very smoky gun to some Marcion-esque interpolators. There's also the issue that half of the Epistles are probably spurious, so it's no shocker to suggest the idea that some people tried to use the name of Paul to suit their own doctrines as time went on.
There's also the issue of the overall reliability of Acts, from which the very basis of Paul's claims are based. There are those who say Luke had a different author than Acts, despite Iraneus' claims.
Historical reliability of the Acts of the Apostles - Wikipedia, the free encyclopedia
If Paul was a true Apostle, the objective evidence is weak and purely relative based on what the individual thinks is "True Revelation" or not. With an historical approach of Yashua's very pro-Torah message (though anti-Pharisee), it's clear to see that unless the "New Perspective on Paul" is correct, they don't match whatsoever. If the "New Perspective" on Paul is accurate, then he was indeed a Pro-Torah Jew whose views were simply misunderstood as Lawlessness later on. (For instance, grouping Circumcision with the rest of the law, as there is no real command to circumcize anyone but your son, Abraham was 90.)
Nonetheless, when Paul was put on trial at the end of Acts, he is not found guilty of preaching any lawlessness. The only resolution for the "Lawless Paul" version is that he lied to the Jews in Jerusalem about his beliefs and didn't actually believe you had to obey the Law. Their view of his taking of the Nazirite vow for the Jerusalem Church must either be that he didn't really believe it and was putting on a show just to "fit in" and that the Jerusalem Church was wrong, or he was indeed responding to rumors of Lawlessness with an honest display of adherence to the Law.
If the Christian Community can accept the "New Perspective" on Paul and that he was pro-Torah, then that would smooth out the doctrinal clashes greatly. This is how I've viewed Paul as recently, but I still can't decide.
New Perspective on Paul - Wikipedia, the free encyclopedia
Particularly important however, that all those who believe in Paul, should take note of is the very meaning of the word "Grace", which should be read as "Favor" as in "favor you have earned for obedience".
So....they don't teach it has to be earned...but it requires effort....yeah....