How can one reconcile a son's desire to study religious sciences and the Arabic language and to memorize the Qur'an, with his parents' refusal of this, on the grounds of focusing on worldly matters and sustenance?

Obeying one's parents in studying a specific major is not a religious obligation. However, one should deal with them kindly and consider their advice as much as possible. Seeking knowledge is not limited to university studies, and there is no contradiction between a university major and seeking religious knowledge. Furthermore, the desire to seek knowledge does not conflict with striving to earn a livelihood by studying a suitable university major.