Jesus said that He would build His Church such that it would ultimately overcome the powers of darkness. But, the Church isn't just a building or an institution, it is really the group of people who are following him.
Life in a Church community is far from perfect. Jesus warned us not to think that we are great. Rather, he shows us that the best path is to follow his example of loving and serving others. He said, "Greater love has no one than this, that someone lays down his life for his friends."