Societal language ideologies affect language education policy implementation through teachers' beliefs, which in turn influence their pedagogical decisions and practices. Understanding the relationship between language ideologies and teachers' beliefs is crucial in multilingual contexts in postcolonial countries such as Namibia. This study explores Namibian mainstream teachers' beliefs about language policy and its implications for teaching and learning through a questionnaire, individual interviews and focus group discussions. The results show that both monolingual ideologies that stress the importance of English, and decolonising ideologies that advocate for the use of indigenous languages, affect teachers' beliefs. Deconstructing the hegemonic ideologies and giving teachers opportunities to reconsider their beliefs would contribute to achieving a more flexible multilingual approach in education.