Sometimes one simply has to play up to cultural standards. Many have pointed out the illogical approach of Paul in Acts: Acts 15 states that circumcision is not necessary, yet Paul circumcizes Timothy; Paul has shown that Gentiles need not follow Mosaic, yet he chooses to make sacrifices at the Temple. Many people point out the inconsistencies in their attacks on Paul.
Yet we often neglect the fact that Paul became all things to all men. Paul saw no need to anger the Jews he was working among in Jerusalem, and thus had no problem offering those sacrifices of cleansing. Indeed, we find Paul taking a Nazarite vow in the context of his Gentile ministry. Paul was a cultural Jew and, as a former Pharisee, was comfortable with the Jewish expression of his faith. For Paul, Jesus was the fulfillment of the Law, not the founder of a new religion per se.
From a missional point of view, you must often dress, eat, and live in ways that conform to the culture you are entering. To not do so would be poor missiology.

Daniel #1-
Good point, and we cannot overlook that Paul does not ask, or even want, Titus to be circumcized (Gal 2). Cultural and theological implications must be considered for each circumstance.

Daniel, an increasing number of New Testament scholars are not convinced Paul’s observance of the Torah is missionary strategy, but a part of his faith, his covenant commitment, and belief system.

Scot-
Who would you include under that heading? (Just wondering; been out of seminary too long!)
I don’t discount that Paul is doing it as a part of his faith; he still sees himself primarily in Jewish terms throughout his ministry. Indeed, he usually goes to the Jews (or at least the synagogues) first. But I still wonder about the strategy of it all. Paul seems to play by the “rules” wherever he is: among Gentiles, he is not above eating in non-kosher ways by eating with Gentiles, and among Jews he seems to keep all of the kosher laws (all the laws of purity).
I do wonder, however, about the continued use of the sacrificial system among Christian Jews during this time. Are they still participating in all of the temple’s sacrifices, even though they saw Christ as the ultimate Lamb of God? (Just wondering…)
~Daniel

Daniel, hard to know about sacrifices.
But the good messianic Jewish scholars are involved, but I think now of Markus Bockmuehl at Cambridge. I suspect this will become an issue, but not central, to NT studies before too long and will generate lots of friction.