Really, you couldn't explain this? In every action Christ does he requires a small ascent/action on our part (The Mass is an act of Christ through the priest who is "in persona Christi"). Money is simply an easy way to show support to the ministry of the priest, by providing a simple offering. I have never heard of a priest denying saying Mass because someone couldn't spot a five dollar bill. When we ask for God's grace it is appropriate to make some participatory action (or act of piety) to cooperate with the grace. How did this article get published in a "Catholic" publication?