This article discusses how to deal with the relations between different cultural perspectives in classrooms, based on a proposal for considering understanding and knowledge as goals of science education, inspired by Dewey's naturalistic humanism. It thus combines educational and philosophical interests. In educational terms, our concerns relate to how science teachers position themselves in multicultural classrooms. In philosophical terms, we are interested in discussing the relations between belief, understanding, and knowledge under the light of Dewey's philosophy. We present a synthesis of Dewey's theory of inquiry through his naturalistic humanism and discuss its implications for the concepts of belief, understanding, and knowledge, as well as for the goals of science teaching. In particular, we highlight problems arising in the context of possible conflicts between scientific and religious claims in the school environment that result from totalitarian positions. We characterize an individual's position as totalitarian if he or she takes some way of thinking as the only one capable of expressing the truth about all that exists in the world, lacks open-mindedness to understand different interpretative perspectives, and attempts to impose her or his interpretation about the facts to others by violent means or not. From this stance, any other perspective is taken to be false a priori and, accordingly, as a putative target to be suppressed or adapted to the privileged way of thinking. We argue, instead, for a more fallibilist evaluation of our own beliefs and a more respectful appraisal of the diversity of students' beliefs by both students and teachers.