It is not the ideas that are dangerous, it is the changes that would be required to believe them. We should never be intimated by a new idea, Rather we should first seek to understand them. Then we can fully consider the implications and determining there worth. Further more in regards to truth, it is better to seek it than to remain blissful and ignorant.
Truth doesn't become false if you don't believe it. Unbelief cannot make it irrelevant, it only makes it dangerous. The reason for rejecting an idea that might be true isn't because it is hard to understand, rather we refuse to even consider them if they presents a moral challenge to how we already live. We claim every logic and reason except the one that we use. If were honest our only argument would be, "I am scared to think of it!" The truth is not that hard to find, though there is more of it than we will ever know. The truth is however, invisible to those who refuse to look.