Mark, the shortest of the four gospels, presents Jesus as the Son of God who crosses the religious and social boundaries of his time in order to extend God's rule to include the outsiders and those who are unclean. It continues to challenge readers to follow Christ across the boundaries that separate people. This commentary, like others in the Chi Rho series, uses language that is simple and clear, avoiding technical terms. It gives an explanation of the text that is sound and reliable, easy to understand without being superficial.