Should all churches and temples be sold to help the poor?

All religions claim to be there for mankind's benefit, so I wondered why such an obscene amount of money is held in the buildings and land they own, when it could obviously go to a better cause than keeping a vicar/rabbi/whatever warm for one day a week. Such a move would make atheists think twice about condemning religion and help thousands of people in dire need. god is everywhere apparently.... why do we need churches?