This piece of scripture contains one of the most confusing phrases in the gospels where Jesus says, "Leave the dead to bury their dead."
Is Jesus really telling a son not to bury his father? I don't think so. What Matthew is saying is that their is an urgency about the Christian life and that a person has to make a real choice; either they follow Jesus or they do not.
However, on a practical level, this saying does have application. If we are friends or familiar with people who have no interest in the Christian life or who want to mock us for trying to follow it, there may come a time when we have to choose to leave them behind and move on.
This may not be nice or pleasant but it may be a choice we have to make. As we grow to love the Lord more and more we shall find we have changes to make in our lives and this could be one of them.