In light of the ongoing discussion in the biblioblogosphere about Jewish Christianity, Ritschl's reconstruction of the early believers in Jesus seems interesting and instructive:
Ritschl presents (1) a Jewish Christianity of the early apostles (sympathetic to Paul and the Gentile mission), (2) a Jewish Christianity (Judenchristen) opposed to Paul and the Gentile mission, (3) and Pauline Christianity, originally sympathetic to Jewish Christianity, eventually deviating from the true understanding of Paul and becoming increasingly legalistic and Hellenized, finally transformed into early catholic Christianity. (2:91)So the first group would be represented in Acts 15, the second must have been the opponents in Galatians whose thoughts were carried on by the Ebionites, and the third eventually won the day through syncretism and codification. What do you think of his reconstruction? Is it possible? Probable?