The gospel for today is taken from the gospel of Mark 3:31-35. Catholics often have to defend the charge that this directly points to Jesus "brothers and sisters", thus the perpetual virginity of Mary can't be true since Jesus had brothers and sisters. Over and over again, catholic scholars have pointed out the fluidity of those terms, the tradition that these are actually Jesus' cousins, and (my own personal belief) that these were likely children by Joseph's former marriages. Of course, both sides miss the larger point that this is supposed to be the beginning of people abandoning Jesus, even the 12, at his crucifixion.
What I find fascinating is that Catholics have not pointed out something else that should put Protestants on the defense. Jesus says that in order to be his mother, brother, and sister, we must "DO the will of God". This is an active verb. It's far from the sola fides of Luther. This is much closer to the notion of James, "Show me your faith and I'll show you my works."