Matthew 6:5-6 has Jesus saying the following:
‘And whenever you pray, do not be like the hypocrites; for they love to stand and pray in the synagogues and at the street corners, so that they may be seen by others. Truly I tell you, they have received their reward. But whenever you pray, go into your room and shut the door and pray to your Father who is in secret; and your Father who sees in secret will reward you.'
The usual talk that I have heard around this text is often centered around pubic/private prayer, and this is a fine conversation topic. One of the things that I would want to highlight is just how subversive this is to economics.
That is right. Economics.
In the days of Jesus, pious Jewish people would give offerings to God through an animal or grain sacrifice. These sacrifices were not things that you could bring form home to offer up. These sacrifices had to meet a set of criteria to be acceptable and so you would buy your sacrifice on site there at the temple. This purchase had a "temple tax" attached to it so that with every purchase you got the sacrifice but also paid the temple. The temple had a monopoly, and monopolies are susceptible to corruption and abuse. This is part of the reason Jesus turns the tables over in the temple - as a critique of the exploitation of the monopoly.
http://www.azquotes.com/quote/714284
And so you may be able to see that when Jesus calls for private prayer, it is not just a critique of prayer for "show" but a subversive act of protest to the economic system of temple prayer. If we stopped paying the temple taxes in order to have the right sacrifice or the right person or the right "words" then the monopoly falls.
The same was true for Martin Luther and his critique of the practices of indulgences (money paid to the church in order to receive favor/forgiveness/blessing). The Church had a monopoly on the sale of indulgences and fell prey to the corruption of being a monopoly.
Prayer has been and will be a tool for justice and action. Or as Gandhi said, “Prayer is not an old woman's idle amusement. Properly understood and applied, it is the most potent instrument of action.”
This is in part what I understand to be the power of prayer. When understood and applied it can undercut entire economic systems. Bring a temple structure to her knees or spark a Reformation.