Marcion was the first to introduce a Christian canon. His canon consisted of only eleven books, grouped into two sections: the "Evangelikon", a shorter version of the Gospel of Luke, and the "Apostolikon", a selection of ten epistles of Paul the Apostle, which were also slightly shorter than the canonical text. Early Christians such as Irenaeus, Tertullian, and Epiphanius claimed that Marcion's editions of Luke and the Pauline epistles were intentionally edited by Marcion to match his theological views, and many modern scholars agree. However, some scholars argue that Marcion's texts were not substantially edited by him, and may in some respects represent an earlier version of these texts than the canonical versions. Like the Gospel of Mark, the gospel used by Marcion did not contain elements relating to Jesus' birth and childhood. Interestingly, it did contain some Jewish elements, and material that challenged Marcion's ditheism—a fact that was exploited by early Christians in their polemics against Marcion.