Ideology helps us understand people s beliefs about specific facts. Scientific denialism describes the psychological state in which the justifications that explain ideological positions become immune to evidence. Scientific evidence and consensus of the scientific community are denied or distorted in the name of values or ideological preferences. It was possible to observe this phenomenon during the COVID-19 pandemic, which transcended the health, economic, and humanitarian spheres, also bringing to light a serious epistemic crisis. The information – and disinformation – epidemic has caused the erosion of trust in science and the search for alternative forms of knowledge, causing statements of ideological nature and a precarious factual basis to become widely disseminated, facilitating the adhesion to conspiracy theories. A review of the scientific literature and technical, historical and journalistic documents was conducted; more specifically, about the psychological, social and political effects caused by the epistemic confusion between science and ideology during this historical period in Brazil. An investigation about how ideological thinking interferes with factual perception was carried out, describing how human cognition is ideologically motivated and how motivated reasoning protects one s identity, making the political ideology select the information that corroborates our worldviews and set aside whatever confronts them. This thesis is composed of four theoretical articles that aim to analyze the relationships between science, ideology, scientific denial, conspiracy theories, conspiracy mindset, ideological thinking and political extremism.