Some follow up from a sermon I once preached on Mark 2:
It is very interesting that Jesus forgives the paralytic "when he saw THEIR [the paralytic's friends'] faith" (2:5). It's as though the man's friends trust Jesus on his behalf -- and that is what impels them to bring their friend to Jesus for healing. What are we to make of this? It seems that that there is such a thing as "corporate faith" in the Scriptures. The evangelical church today rightly emphasizes our need to make a personal response to Jesus. But faith also has a communal aspect, and you see this come out frequently in the gospels, where one person's faith procures blessings for another person. For example, we find parent figures (e.g., the centurion in Mt. 8 and the Syro-Phoenecian woman in Mt. 15) who believe the gospel on behalf of dead or demon possessed children -- and the children are rescued on account of the parents' faith. The same thing happens in baptism -- parents believe the gospel on behalf of their children, and thus bring their children to Jesus (who has promised to offer himself and his benefits in the sacrament) for blessing. The faith of the parents acts on behalf of the children and obtains something for the children.
None of that suggests that the paralytic did not have to trust Jesus on his own, as an individual. He did -- and I think we can assume that in this very story, he puts his faith in Jesus. But we should not let individual faith keep us from seeing faith's broader, wider dimensions. We are not isolated atoms, floating in space. Rather, we are molecules -- we are all attached to other people. The paralytic's friends form a faith-community, in which the paralytic himself can be brought to faith. Faith is always begotten and nurtured in the context of relationships with other believers. Yes, we have to believe the gospel for ourselves, as individuals. But faith ordinarily comes to fruition as we get immersed into a community of faith, as was the case with the paralytic in Mk. 2.
Applied to families, this is why the whole notion of "growing up Christian" makes so much sense. Of course Christian children share their parents' faith. They might shipwreck that faith later on in life, especially if they get tangled up in a different community that rejects and mocks the gospel. But children who are born into a believing household start off as believers themselves. They share in the corporate faith of the family. As parents "believe the gospel for their children," their children receive benefits from Christ, and the parents seek to nuture the faith of their children unto maturity. By faith and in faith, parents continually bring their children to Jesus for forgiveness and renewal, just as the paralytic's friends brought him. Yes, the child must also learn to own the gospel for himself, to personalize the covenantal relationship. But even that individualizing of the gospel promises happens against the backdrop of the wider communities of family and church -- not by escaping them.
Similarly, those who come to Christ as adult almost always do so in the context of relationships -- an "alternative family," if you will. They convert, not merely because they hear an amazing sermon or read a book (though those things may be useful and necessary means), but because Christians reach out to them, befreind them, and (over time) enfold them into the community of the gospel. For adult converts, becoming a Christian is never a matter of simply changing ideologies or worldviews; it means changing whole social networks and communities as well. Becoming a Christian is not just embracing Christ, but embracing (and being embraced by) a whole new set of friends. Coming to faith is inevitably deeply relational. This is why one of the best evangelistic strategies you can use is to invite a non-Christian friend to Christian events (including worship). Your non-Christian friend may feel a bit uncomfortable or disoriented (especially in worship), but the personal contact that takes place provides an opportunity for understanding to grow. The relationships allow truth to get a foothold, and over time, lead the person to consider making the faith his own. Non-Christians need to experience the Christian commmunity in action as much as they need to hear the gospel proclaimed. As they see how Christians live and interact, they can begin to imagine themselves as Christians too, and the possibility of faith opens up for them.

On another note entirely-- In my sermon I mentioned the irony involved in Jesus and the leper swtiching places. Irony is actually a major literary tool in Mark's gospel. It's easy to miss because we are not always accustomed to looking for these techniques in biblical texts. Perhaps we read the Bible too "seriously." In truth, God is winking at us from time to time, as we read his Word! The political philosopher Thomas Hobbes was the first modern reader of Mark to discover irony, which he found by comparing Mk. 15:30 with Mk. 8:35. Since then, there has been an ever increasing interest in examining  and analyzing the Bible from a literary point of view. 
If you study Mark closely, you will detect irony all over the place. When I was a student at the University of Texas, I wrote a paper on this topic, entitled "The Ironic Gospel": Most of that paper is a philosophical analysis of how irony works, and most likely won't be interesting to you. But the first several pages catalogue examples of Markan irony, and may serve to enrich your reading of the Bible.
In that essay, I was building off of the work of Jerry Camery-Hogatt, who wrote a study on Mark's use of irony. But Mark is not the only inspired writer to employ irony as a literary technique. Several biblical books are heavily ironic and full of subtle understatement. Another helpful study is Paul Duke's Irony in the Fourth Gospel. Paying attention to literary features like this helps us to "read the Bible for all it's worth." God intends for the Bible to shape us not only through its content, but also by its form (or literary packaging). The Bible always repays the careful reader.