You are assuming that because there are some corrupt members, the whole premise is flawed. Yet, you wouldn't say that the justice system should be abolished because of a corrupt judge, or that democracy is bad because of a corrupt politician. 

There are a number of corrupt members in the Catholic Church. That doesn't make all the rest corrupt, or the Church's teachings invalid. There are also many many virtuous members, who strive to live a holy life and help others, but you deliberately choose to ignore those because they don't serve your argument.