Building on recent scholarship that argues for a second-century date for the book of "Acts", "Marcion and Luke-Acts" explores the probable context for the authorship not only of "Acts" but also of the canonical "Gospel of Luke". Tyson proposes that both "Acts" and the final version of "Luke" were published at the time when Marcion of Pontus was beginning to proclaim his version of the Christian gospel, in the years 120-125 C.E. He suggests that although the author was subject to various influences, a prominent motivation was the need to provide the church with writings that would serve in its fight against Marcionite Christianity. Tyson positions the controversy with Marcion as a defining struggle over the very meaning of the Christian message and the author of "Luke-Acts" as a major participant in that contest. Tyson concludes that the author of "Acts" made use of an earlier version of the "Gospel of Luke" and produced canonical "Luke" by adding, among other things, birth accounts and postresurrection narratives of Jesus.