Test everything, hold on to that which is good. These are the words of 1 Thessalonians 5:21. Sadly, some Christians fail to yield to it. As Paul says in Ephesians 4:14, they are "tossed to and fro and carried about with every wind of doctrine". To these people, anyone deemed an authority must be believed without question, and anyone who disagrees with these people must be automatically ignored.
I once knew an extreme example. We'll call her Sally. Sally would jump around between churches, never really settling on one. She initially became a "Christian" because Justin Bieber said he was, and that Job was the most inspirational person in his eyes. She went to the local Anglican Church for a short while, but later took me "church shopping". We passed the local Spiritual Church, and she got cross with me for suggesting that, since they talk to spirits, as the Bible forbids, they might not be Christian. Then, by coincidence, she met the same Mormon missionaries I was witnessing to at the time. She became very attracted to one of them, and suddenly, Mormonism was the absolute truth. Until he rejected her, and it eventually wasn't...
She may be an extreme example, but she represents a mindset that is very common within the Church. Tricksters and wolves in sheep's clothing can say almost anything, you can guarantee someone will believe it. Take, for example, the doctrines of Joel Osteen. Osteen's teachings have made him a very rich man. How? Because people buy it. They quite literally buy his teachings. Yet the prosperity gospel, which he preaches, is no gospel at all. Osteen sees God as a being who wishes to pamper us right here, on Earth, while the Bible gives us no such impression. It teaches us that we will have trials and tribulations in this world, and that we should be willing to give up everything to follow Jesus.
Don't be tossed about by every wind of doctrine. Whether church or preacher, denomination or individual, book or website, test everything, and hold on to that which is good. Anything short of this is just childish.