What is the most dangerous heresy that exists in the church today?

There are many heresies referenced in the New Testament and even more that have surfaced in the centuries since it was written. One is alluded to in the account of Simon Magus. > 9Now there was a man named Simon, who formerly was practicing magic in > the city and astonishing the people of Samaria, claiming to be someone > great; 10and they all, from smallest to greatest, were giving > attention to him, saying, “This man is what is called the Great Power > of God.” 11And they were giving him attention because he had for a > long time astonished them with his magic arts. 12But when they > believed Philip preaching the good news about the kingdom of God and > the name of Jesus Christ, they were being baptized, men and women > alike. 13Even Simon himself believed; and after being baptized, he > continued on with Philip, and as he observed signs and great miracles > taking place, he was constantly amazed. > 14Now when the apostles in Jerusalem heard that Samaria had received the word of God, they sent them Peter and John, 15who came > down and prayed for them that they might receive the Holy Spirit. > 16For He had not yet fallen upon any of them; they had simply been > baptized in the name of the Lord Jesus. 17Then they began laying their > hands on them, and they were receiving the Holy Spirit. 18Now when > Simon saw that the Spirit was bestowed through the laying on of the > apostles’ hands, he offered them money, 19saying, “Give this authority > to me as well, so that everyone on whom I lay my hands may receive the > Holy Spirit.” 20But Peter said to him, “May your silver perish with > you, because you thought you could obtain the gift of God with money! > 21“You have no part or portion in this matter, for your heart is not > right before God. 22“Therefore repent of this wickedness of yours, and > pray the Lord that, if possible, the intention of your heart may be > forgiven you. 23“For I see that you are in the gall of bitterness and > in the bondage of iniquity.” 24But Simon answered and said, “Pray to > the Lord for me yourselves, so that nothing of what you have said may > come upon me.” Jesus clearly said that we cannot serve God and money and he cleansed the temple of money changers. The way money is handled in Christianity is the source of much confusion and heresy in the church today. Christianity can be a big and profitable business and many ministers acquire great wealth through it. Are there other heresies common in Christianity today that may affect people even more negatively than a money based heresy?