This book argues that Mark's gospel was not written as late as c. 65-75 CE, but dates from sometime between the late 30s and early 40s CE. It challenges the use of the external evidence (such as Irenaeus and Clement of Alexandria) often used for dating Mark, relying instead on internal evidence from the gospel itself. James Crossley also questions the view that Mark 13 reflects the Jewish war, arguing that there are other plausible historical settings.
Crossley argues that Mark's gospel takes for granted that Jesus fully observed biblical law and that Mark could only make such an assumption at a time when Christianity was largely law observant: and this could not have been later than the mid-40s, from which point on certain Jewish and gentile Christians were no longer observing some biblical laws (e.g. food, Sabbath).