Materialism has officially become dangerous in my eyes. Not in any way to the extent of Islamic extremism, fascism, or other rising positions in the world, but dangerous nonetheless. Why?
1. The death of skepticism: even the slightest skeptical questioning casts doubt on materialism, for how can we reduce the mind to matter when we know the mind directly and matter through it? Can we trust our senses that there's a physical world out there? Is there really no other valid possibility in the world? Skepticism is about doubt whereas materialism is a position of certainty. There's very little questioning of it and that questioning is dogmatically brushed off rather than addressed. With the increasing popularity of materialism this is very dangerous.
2. Neglect of the mind and its role in health and happiness is dangerous. Even just the simple way we perceive our situation has an effect on us, such as whether we believe we are happy or not. To have any hope of treating the mentally ill we need to address both mind and brain, not simply the latter. We have to address subjective symptoms, not simply what physical ailments are immediately noticable.
3. The rejection of all immaterial things completely destroys concepts such as math and logic. In materialism these things must be mind dependent, where they exist as concepts, at least according to materialism. But the idea that things like math and logic, which lead us to objective truth and intelligent thought, are mind dependent is extremely dangerous. It basically allows for whatever one wants to be true to be treated as true, because logical and mathematical truths are more or less subjective and fabricated. Any group that teaches things like logic to be relative posses a threat to knowledge and growth. An ignorant community is one ripe for the plucking!
4. Life-Fields are another thing rejected by materialists. Despite being confirmed by thousands of experiments, and leading to massive break throughs in medicine like predicting ovulation, materialists reject the idea of L-Fields, and in fact likely never have heard of them due to them being ignored in mainstream science specifically for not fitting with materialism (see #1). Life-Fields can help us predict things like ovulation, cancer, birth defects in a developing egg, highs and lows of mental stability, even things like when would be the best time for someone to learn something. The benefits to human life could be so numerous, but alas since L-Fields bring questions like Teleology and design to the table, they are simply ignored by materialists who care neither for scientific truth nor human life.
5. Materialism greatly implies a belief in hard predeterminism, as there is nothing to stand against the every flowing onslaught of nature. If this this the case there's simply no hope in ever changing or improving upon any situation. Why would we go to a doctor or see a counselor if nothing we do can actually change anything? Of course some realize, almost self evidently for many of us, that we can indeed go against the flow of material nature. We can manipulate it such as to make medications in this example, or use the strength of our mind to recondition the way we act and think. These being only two small examples!
Now sure, materialists are not going around killing people, I'd never pretend they're as bad as extremist groups like ISIL. But materialism is dangerous in a much longer run, it's taking over culture far more quickly than ISIL could ever hope to, and it's ingrained in us for most of our lives, stuck as part of our education systems, dominating the way we view and treat human life. There may not be genocide, but it's still dangerous nonetheless. It's led to a death of doubt and questioning, led to a rejection of the power and independent existence of the mind, it is forced to push a view of logic and mathematics (which sciences like physics rely on) as mind dependent and therefore not objective or real, it ignores hard science that can benefit humanity simply so that it's authority as leading philosophy cannot be questioned, and it leads to a point of nihilism where we may as well wallow in our problems because nothing can stand up to the flow of the material world.